I take my linguistic examples wherever I come across them. In this case, the data comes mostly from porn. (Warning: a lot of sexual acts will be alluded to in very plain language in this posting.)
The story begins with a young man crying out
(1) Oh yeah, shoot my ass!
at the climactic moment of a segment in the gay porn compilation video A Bronco Named Brad (on the video, see here). The speaker is asking his partner to
(2) ‘shoot [your cum] on my ass, ejaculate on my buttocks’ [ONTO reading]
(It’s a convention of porn films, gay and straight, that the money shot must be visible to the viewer, so that guys come on someone else’s body or on their own, or occasionally on the furniture or whatever — see me on mess here. In gay porn, a fuck scene often ends with the fucker pulling out and coming on his partner’s buttocks, staying in situ but displaying his ejaculation.)
In other contexts, (1) could convey
(3) ‘shoot [your cum] in(to) my ass, ejaculate in(to) my anus’ [INTO reading]
Note the two different senses of ass here — ‘buttocks’ or ‘anus’, with the anus being the centerpiece of the buttocks, so to speak — related metonymically.
((1) on the INTO reading describes the culmination of bareback fucking, without the pull-out, so its natural home is porn writing, not porn films.)
But now for the main linguistic point, shoot ‘ejaculate’ used, exceptionally, as a transitive verb.