Try this to "Blast off" his whole leg.
Press C
Contract Left Hip
Extend Right Hip
Contract Knees
Extend Ankles
Space x 1
Extend Left Knee
Contract Left Ankle
Space x 1
I made my own little one too, this should break of BOTH of his knees
Hold all
Contract both hips
Contract both knees
Extend both ankles
Press space
Now press Shift + Space(x3)
Extend both knees
Press P or try to finish
It should kick very hard and kick right on both knees and break them off and if u dont mess around with it at the end and just press P, uke should do a complete backflip.