Slang for a penis because as one cums, (unless you're really fucking old or have had some sort of injury) the first few orgasmssquirt.
Johnny McWarguy: Hey Jen, wanna see my squirt gun?
Jen: Uhhhm... ok?
Johnny McWarguy: *unzips pants and squirts his load in Jen's face*
Jen: ...I'm going to kill you.
Its when you put Duct Tape around your cock and piss hole and then Violently Masturbate so that when you climax your Cum has nowhere to go, like a Broken Squirt Gun,(Squirt Guns would always jam up with water)