I like clap push ups for the upper body.

My other favourite is to get a mat and from standing drop onto my back as quickly and as smoothly as possible (bending knees a lot) then by using a fairly strong contraction of my abs spring up again without allowing my feet to go out to the side (that would strain my knees).

Once I'm up I immediately add a jump straight upwards at the end of the movement.

When i'm tired I sometimes fail to get enough power out of my abs to get up with enough momentum and I have to roll back onto my back and try again. it's a hardie but a goodie .