Warp

For gamers looking to boost this achievement:

Just like the solutions below state, you need to have a friend on the Challenge leaderboards with a gold time or better then you have to beat their time. Because I was impatient and didn't want to ask the slowest 50 people for a Friend Request, I have created a dummy account under the name GlancingDruid99 (XBL appropriated account handle) for this sole achievement which anyone can try to beat to pick this up.

Step 1: Complete the game on Adventure (or at least until you unlock the 3rd Challenge room, about 10-20min of the game in)
Step 2: Send a FR to GlancingDruid99 then PM me ('MugenKairo') on TA or XBL and i'll jump online and accept the request under the dummy account.
Step 3: Once you are on the friends list load up the 3rd challenge room 'Advanced WARP challenge room' and try to beat my time of 0:00:20.504. The gold time is 21.0000 seconds so if you can beat both times this achievement will be yours. I would suggest not even trying for Gold until you have a friend who already has Gold on the leaderboards.

The Gold rating for the challenges are very challenging but with patience and practice I found the 3rd challenge room to be the easiest to beat. Although I can't find a video on Youtube, once I have my Vid Capture set up I'll add my own Gold Challenge run into this solution. For everyone trying this, I took the left fork through the lasers, then veered right down the stairs past the canisters (which I didn't use) then through the soldiers to the end. With only a little practice it shouldn't be too hard to beat

EDIT: Saije7 managed to pop the achievement on 12 May 2012 which means that a gold account which has reverted back to Silver will still maintain its standing in the leaderboards, hooray!

EDIT X 2: Many gamers have said that they have popped the achievement while the FR is still pending. As this is not a one-off it is fair to say once you have sent the FR to the dummy account, go for Gold without waiting for a confirmation. This is a bonus for me as I no longer have to keep checking the dummy account :D

Best of luck to all!

You need to beat a friends gold time on a challenge.

Here is my youtube video of me beating this on challenge 3.

Thanks to MugenKairo for being my friend so i can earn it.

What I did was go to the leaderboard for a challenge I hadn't completed yet and sent a friend request to the gamertag with the slowest time that was still Gold. If they accept it should be easy to beat their time - but you have to quit to dashboard and reboot the game with the player already on your friends list first, or else the game won't register the achievement