These actually exist for some reason. They don't fire or anything, it's just a poorly made pocket knife that's difficult to do anything useful with and it will probably get you shot by the police lol
Ah, ye olde gunblade. Despite being a collector of weird and novelty knives, somehow I still don't own one of those.
I will add that one time many years ago, I took an offhanded joke from a forum post (remember those?) and developed a functional rocket propelled machete. I'm certain the video of it is still out there on the early internet somewhere. It was just bodged together out of model rocketry components and a $5 machete from K Mart. Duct tape was involved. It didn't work very well but it was worth it for the gag.