Re: Riker in First Contact (episode, not the film)
that's if the slots are compatible. lol..
For all one knows inserting may lead to an infection or worse. And not in a bad way, but a "slot" of an alien female may contain material only biologically compatible with males of her species.
Voyager's EMH implied that intimate relations with a Bolian can be hazardous to a human's health.
"I was never a Star Trek fan." J.J. Abrams