Army of Two: The 40th Day

This achievement is called Paper, Rock, Scissors. To win the achievement, you must press Y near your partner and not in combat to have the mini-game function. You must then win the mini-game 3 times in a row against your partner for the achievement to unlock. I am unsure if you must have a human partner or this can be done with the AI. I did this with a human partner though. My partner and I just had to choose the same option three times in a row and then do the same for my partner to win unlock it.

This is easily done with the AI as he aint that smart. he will always try to beat whatever u chose last round. so if last round u chose rock he will choose paper nxt round therefore you pick scissors and so on.

Easiest way i done this was to do it with a friend in co op as i found it hard beating the AI. Start up a chapter in co op with a friend and as long as you are not in Combat press Y button and begin playing Rock, Paper, Scissors game.
Paper beats Rock
Rock beats Scissors
Scissors beats Paper

Just choose a way to win 3 times on the trot

Its easier with a friend, but if ure like me where none of ure friends have the game yet, the AI has a patern try to memorize ure AI partenrs order and it should take u a couple of tries just win against him 3 times in a row. If anybody wants to boost these co-op achievements send me a friend request or a message. Peace

I actually literally just did this with the AI opponent after reading the achievement. It's SUPER easy. Just walk up to him hit Y youll get the icon that shows the d-pad press up for scissors, left for rock, or right for paper your choice. You'll learn by playing it that When you do win once, he will try and beat whatever you won with last and this makes the achievement easy to obtain. You can just random pick something until you win once and then the next thing that he chooses generally will be what is needed to beat what you won with last. Example I beat his scissors with a rock, so the next move for him will be paper, yours should be scissors so his next move will be rock, and yours should be paper and it will pop no problem.