Bed bugs are about as good a candidate as any:
The bed bug penis is adapted to stab. The male bed bug … climbs onto his lover’s back, his head draped casually over the equivalent of her left shoulder and his body curved around hers in a violent embrace. He next aims his pointy member not at her genitals, the target choice of more reasonable animals, but at the right side her abdomen. There, he stabs her, ejaculating directly into her body cavity. Scientists call this traumatic insemination. I call it rude.
But why not aim for the perfectly good genitals?
[T]he strongest hypothesis relates to the mechanics of the female’s sperm bags. The last sperm in is the first to make it to the ovaries; the last male to mate with a female, then, gets to cut the paternity line. This may help explain why each male mates with such frequency—between 20 to 25 times the amount necessary for the female to produce the maximum number of eggs.
The Dish 