Prank in space.
On the last Hubble repair mission, they should have rigged and alien head to pop out of the access panel. Can you imagine these guys, up there now, opening it and a big-eyed alien mask pops out at them?
It would probably give them a heart attack or send them flying off into space, so maybe it is good that wasn’t done.
Practicle jokes are probably best left on the Earth. Has one ever been done in space?