(Verb:) To have sex with a redhead, usually on her period so that the penis becomes red. Immediately before ejaculation, you pull out and explode on her firecrotch, and "put out the fire"
Blythe: Yo man, I'm going to palm springs to firetruck some bitches
Akakios: But everyone in palm springs is gay or old
Blythe: Fuck you, Puta
Emil: Hey man how's it going?
Michael: not bad, you?
Emil: well, you're sister started getting lippy
with me and I noticed she was a redhead so I firetrucked her
Nick: hey, huey, you're mom's on her period right?
Nick: you think I could get her drunk enough to dye her pubes red and then let me firetruck her
Huey: Only if you get some king cobra