happy wheels controls 

Up = Accelerate Forwards
Down = Reverse Backwards
Right = Tilt Clockwise
Left = Tilt Anti-Clockwise

Space = Action Button!
Once ejected, you can grab with spacebar
Wheelchair Guy: Boosts
Segway Guy: Jumps
Irresponsible Dad: Brakes
Effective Shopper: Jumps
Moped Couple: Boost for a limited time
Lawnmower Guy: Jumps
Explorer Guy: Locks onto rail (silver track)
Santa Claus: Flies for a limited time

Shift: Second Action Button
Wheelchair Guy: Rotate rocket anti-clockwise
Segway Guy: Straighten legs
Irresponsible Dad: Eject father
Moped Couple: Eject Woman
Explorer Guy: Lean forward
Santa Claus: Cuts elves lose when they die/lose legs
http://unblockedallgames.com/unblocked-games/happy-wheels
Ctrl: Third Action Button
Wheelchair Guy: Rotate rocket clockwise
Segway Guy: Bend legs
Irresponsible Dad: Eject child
Moped Couple: Brake
Explorer Guy: Lean backward

Z: Eject everyone in vehicle

C: In a vehicle with two characters, change who to view.