Empty Gesture
Not unlocked yetDrop your co-op partner in goo while they are gesturing by removing the bridge under them
Party of Three
Not unlocked yetFind the hidden companion cube in co-op test chamber
Narbacular Drop
Not unlocked yetPlace a portal under your co-op partner while they are gesturing
Portrait of a Lady
Not unlocked yetFind a hidden portrait
Good Listener
Not unlocked yetTake GLaDOS' escape advice
Rock Portal Scissors
Not unlocked yetWin 3 co-op games of rock-paper-scissors in a row
Preservation of Mass
Not unlocked yetBreak the rules in Test Chamber 07
No Hard Feelings
Not unlocked yetSave a turret from redemption
Lunacy
Not unlocked yetThat just happened
Triple Crown
Not unlocked yetSolve 3 co-op chambers in the Mass and Velocity course in under 60 seconds each
Overclocker
Not unlocked yetComplete Test Chamber 10 in 70 seconds
Friends List With Benefits
Not unlocked yetWhile playing co-op, hug 3 different people on your friends list
Stalemate Associate
Not unlocked yetPress the button!
Still Alive
Not unlocked yetComplete Course 4 with neither you nor your co-op partner dying
Talent Show
Not unlocked yetNever lose a cube in Chamber 6 of the Mobility Gels co-op course
Wake Up Call
Not unlocked yetSurvive the manual override
Asking for Trouble
Not unlocked yetTaunt GLaDOS in front of a camera in each of the five co-op courses
Gesticul-8
Unlocked atPerform all 8 gestures of your own volition in co-op
Professor Portal
Not unlocked yetAfter completing co-op, complete Calibration Course online with a friend who hasn’t played before
Team Building
Unlocked atComplete all test chambers in the Team Building co-op course
Tunnel of Funnel
Not unlocked yetMaster the Excursion Funnel
Dual Pit Experiment
Not unlocked yetDo the same test twice
You Monster
Not unlocked yetReunite with GLaDOS
The Part Where He Kills You
Not unlocked yetThis is that part