Been there, got the t shirt! I was refitting the battery after recharging, 11 year-old daughter sitting in drivers seat. Fitted neg terminal, then just as I fitted pos terminal said daughter hit the horn button - back of head hits underside of bonnet - OUCH!!! - which releases the bonnet stay. Bonnet starts downwards movement towards my totally unprotected back - male part of bonnet catch impales itself in my spine, causing my (also unprotected) head to jerk upward to connect (again) with underside of bonnet.
Attempted to extricate myself backwards from the now half-closed bonnet, only to find that the back of my belt is now hitched on the protruding male (couldn't be anything else could it!) bonnet catch. Attempting to lift bonnet with hands above my head I realise that the hook of the safety catch is now firmly engaged with a belt loop on my jeans - oh god! I am totally trapped.
Daughter meantime has tripped off up the road to play with her friends, despite my fading screams for help. Finally next door neighbour, after looking out several times, decides I'm not doing something highly secretive in my Sierras' inner guts, comes out to ask "You ok in there?" Had I been able to wield a large hammer at that point I would happily have brained him!!!