Left 4 Dead 2

You need to have 2 people (or a second controller) to do it this way.

Find some adrenaline, and then find a ledge. Have the second person walk off the ledge, then have the first use the adrenaline and pick them up. Have the second person walk off the ledge again and repeat the process until the adrenaline wears off, then maybe one more time, just in case you can get one off the tail end of the adrenaline.

You can do this 3 to 5 times per adrenaline shot if you do it quickly enough and they will all count for the achievement.

EDIT: This still works as of Aug 30, 2014, thanks BRARROW for letting me know.

EDIT: Just did this with my girlfriend, she got 5 revives in one shot, so it is possible t get up to 5 revives with one shot if you do it quick enough.

I found this out on the Hard Rain campaign, a teammate got hit to the dock by the tank, and I used the adrenaline shot to see if it would count, I had him walk off the dock 2 more times, and checked the achievement progress and found out all 3 revives had counted.

EDIT: It has pointed out to me that doing this on Dead Centre Survival mode is a good place to go as there are several adrenaline shots you can use. When doing it here have both of your human players grab adrenaline so when one shot wears off you could just have the other one given to you.
Thanks splicegraph for the tip

EDIT: Some people reported having trouble getting this, and found out that you have to do this by walking off the glass paneled walkways, rather than the stairs. (forget who said that, but it was before the site went down, sorry I can't attribute this tip to whoever said that).
EDIT: This tip is courtesy of DragonYen. Thanks for the tip, apparantly your comment was restored, so I can finally accredit you with the tip you deserve :)

EDIT: It has been pointed out that the AI sometimes will interfere with you reviving the teammates. Simply grab the auto shotgun in the beginning and down one person, rather than reload just grab the same one and it should be fully reloaded for you. You should be able to down them before the fully heal, if not you'll have to do it again. While the second AI is picking that person up, shoot them down. When they are both incapped you will be able to do this without any interferrence.
Added this courtesy of SnelleSjonnie.

Have you and a guest signed in. go into a survival match at the dead center level. pick up a adreniline shot. have the guest go up 2 floors and stand on the railing. pull your adreniline shot out and stand in front of the guest and hold down X. On the guest controller you just hold foward and you will revive the guest like 4-5 times in one shot. i found this to be the easiest and the fastest way to do this acheivement.

quick and the dead plus shock jock.

The best stage to pick for this achievement is the HARD RAIN campaign chapter 5 TOWN ESCAPE . When you start in the safe room there is always a defibrillator for the SHOCK JOCK achievement, really good weapons, and most of the time there will be an adrenaline or two for THE QUICK AND THE DEAD achievement as well. Also if you have an extra controller and sign in a guest you don't have to try and lure the bots out of the safe room. Change the difficulty to expert and kill the other survivors and leave your guest standing. Then take the guest out of the safe room and shut the door. Wait for it to die and be sure to grab a defibrillator and an adrenaline if its there. Change the difficulty to easy and kill the zombies but try to to leave at least one alive. Then revive your guest and go back into the safe room. Sometimes another hoard will come so you might not need to change it to expert but if it doesnt you can change it to expert if you want to. Make sure your change it back to easy before your guest dies you want it alive but incapped. Go out and clear out the zombies but if you have another adrenaline in the safe room try to leave a zombie alive so you can do it again. Then take your adrenaline shot and pick up your guest. Once you have used up your adrenaline shots change it to expert and kill your guest or find a zombie or you can go over the downed fence through the gas station and jump in the lake its an instant kill so you can start the chapter over and do it all over again.

This was the way I found to be most reliable to get both achievements quickly. Any questions send me a message via xbox live. GT LBCeroy

It's fairly obvious how you get this legit, but if you want to boost it... well, it's not as easy as you would think. If you down a teammate and then try to revive them, it won't count towards the achievement.

However! You can do this quite quickly if you'd like. Pick The Park in the Parish campaign and run towards the trailer that you have to enter before the crescendo. There should be adrenaline in there, but if you pick some up along the way, that will obviously work as well.

So, you have adrenaline, you're in that trailer, and you haven't stepped outside to start the crescendo. Switch to expert and kill one of the bots, making sure not to down the other two. You can soften them up a bit, but you can not down them even once or reviving them will not count until you restart.

Now open the door, step outside to start the alarm, and step right back in. Let the zombies down one of them, the other bot will try to pick him up, and in doing so, the zombies will down him as well (remember, you're on expert, so this takes no time). Switch to easy if you like, clear the room as much as possible, use your adrenaline, and pick them both up.

Repeat as needed, and achievement unlocked.

LBCeroy's solution works great with one caveat. When I played, I had to die then completely reload the level for it to count. If I died and tried right away again, none of my revives after the first load counted toward the achievement. Just to be safe, always reload the map. Knowing this would have saved me over an hour of work.

To make this as simple as possible, use this method:

1. Have 4 Real players; Be it You and 3 Guests/ You & Friends, Or any mixture :)

2. Load Survival
- Dead Centre, Mall Atrium
3. Take 1 Dummy Acc and take them all the way to the last floor of the stairs, Make them fall off slightly so they start hanging off, NOT DIE.

3. Give yourself Adrenaline and revive them, quickly make you dummy fall off and your main revive them again and repeat.

4. You roughly get 4 revives with 1 shot of adrenaline

Simples :)

Here is a good video to have a visual.

If you would like to boost and use 2 controllers, start a versus match on The Concert Finale of the Dark Carnival (chapter 5) with you as the human and the 2nd controller as the infected.

Kill off 1 of the unneeded survivors leaving only 2. On those towers in the bleachers there should be a defibrillator on each one (2 total) and MOST OF THE TIME, not always, 4 speed shots where you turn the music on in that little booth on the stage. Just blast your team till they have little life and finish them off with that infected controller. Let one die before they go get heath on their own and leave one on the ground bleeding. You can keep reviving the same survivor with the speed boost all 4 times but you can only use one defib per survivor.

So when your done with all the speed boosts let that 2nd survivor die and defib both of them. Sounds like a lot of work but as soon as you do it the first time the second time and third are a breeze, it's the easiest way I've found so far. If you have problems with the survivors healing, just injure yourself in the beginning real bad and use them all right away yourself. It should only take 3 games total for the speed boosts, and 5 for the defibs.

If you have a question about this guide please ask, or if I left something out that's important let me know.