Co-Op Achievements and Trophies
Perform 2 aerial gestures before touching the ground in co-op
Anytime you are launched through the air, press up on the D-Pad to perform an aerial gesture.Do it twice before hitting the ground and this is all yours.
Asking for Trouble
Taunt GLaDOS in front of a camera in each of the five co-op courses
At the end of each test chamber, there is a camera that GLaDOS uses to keep an eye on you.Just make sure you remember to give her a wave, laugh, or any other gesture at least once in each of the 5 courses. Once you perform the final one in course 5, this will unlock.
Complete all test chambers in the Hard-Light Surfaces co-op course
Simply complete all the test chambers in Course 3.
Can't Touch This
Dance in front of a turret blocked by a hard light bridge in co-op
There are a few times you can get this, but Course 3, chamber 6 is the earliest.When you raise the hard light bridge to block the turrets allowing you to go up the stairs, stop for a second and do a little dance in front of the turrets using your gesture menu.
Complete all test chambers in the Mass and Velocity co-op course
Simply complete all the test chambers in Course 2.
Drop your co-op partner in goo while they are gesturing by removing the bridge under them
This can be done in Course 2, test chamber 1.Simply create a portal that extends the light bridge across the goo pit and have your partner walk along it.Have them gesture and then remove the bridge for your reward.
Four Ring Circus
Enter 4 different portals without touching the ground in co-op
There are many ways to go about doing this, but the easiest way is in Course 1, test chamber 1.Have your partner drop 2 portals on the floor and then you drop one beside theirs and one on the ceiling above their middle portal.Drop into yours on the floor and then fall into the middle one.When you are launched towards the ceiling, fire another portal, the same one you had on the ceiling, in front of you and go through it.This will make the achievement/trophy pop.
Friends List With Benefits
While playing co-op, hug 3 different people on your friends list
Once you finish co-op, you will have the ability to use the hug gesture to latch onto other players.For this you will need to hug your partner and then 2 other people on your friends list. Everybody loves robot hugs so give it a shot!
Perform all 8 gestures of your own volition in co-op
This will come eventually as you progress through the 5 courses.Once you reach the final course, your eighth and final gesture is unlocked.
Celebrate your cooperative calibration success
At the end of the calibration at the start of co-op, you will automatically high-five your partner unlocking this reward.
Never lose a cube in Chamber 6 of the Mass and Velocity co-op course
During Course 2 chamber 6, the second part of the test will have you or your partner pressing a button that will drop a cube.When the cube drops, it will hit a pad and launch the cube towards the water below. The trick is to have the other player launching around the room on the kicker pads and through the two portals that you set up on the angled platform and the wall to the left of the pedestal button.Once the other player is flying through the air in a loop, press the button as the other player passes under the cube chute. If timed correctly, as the other player passes through the angled platform portal, he will nab the cube.Take the cube over to the exit and the achievement/trophy is yours.
Place a portal under your co-op partner while they are gesturing
As easy as achievements/trophies can get.Simply have your partner on a portalable surface and have them gesture. Shoot a portal under them so that they fall through and Bob’s your uncle.