If you're going to smash a guitar you have to do it right.
I used to mess around with a bunch of friends in the 80's doing Bonzo dog stuff with an anything goes acoustic sort of vibe. We had one guy in the band who was musically retarded. He couldn't sing or play a note in tune or in time. He was funny as hell though and came up with what he called the "Gaelic synthesiser", basically an old tea chest with all those percussion instruments and novelty whistles etc in there. He'd reach in while we were playing and just mess around with whatever he had. Anyway he wanted to play guitar too so me having an endless supply of beaters took the back of one and rigged it up with a few fireworks and firecrackers set to a simple fuse and trigger in a foot switch. Testing went well and it went with a safe and controlled bang with a few sparks and some smoke.
Well, on the the production model for the gig I over cooked the explosive recipe a bit. As he hit the switch the resulting explosion blew the soundboard into a million bits and knocked him sideways off his stool and took half his hair with it. He was deaf for at least a fortnight.
Best thing of all there was two cute girls in front wearing tight white cotton dresses both with a pint of Guinness in their hands. The bang scared them shitless and resulted in them tipping the beverage all over themselves. We got a free wet T shirt show into the bargain. We never repeated the exploding guitar episode but when we meet we still laugh about it.
Trashing a guitar can be cool you just have to think it through.