The needle went into his sack and extracted semen, which she then flushed into her cooter.
It's not rocket science.
I have a lesbian 2nd cousin who got a daughter from a home job like this. Y'know except that the semen was donated rather than stolen, but the lad was gay as well, just a friend, and their genitals weren't even in the same room.
It's how/why they do it like this with valuable horses at the stud farm. Apparently the speed with which a horse can do it, there's an actual a decent chance of the penis snapping off if anything goes aerie or off kilter by a couple degrees.