Traumatic insemination can lead to compromising genetic situations. Because pirate beetles inseminate traumatically, it has been suggested that the males, like some other arthropods, could have sex with each other to eliminate competition in mating. Pirate beetles have penises like hypodermic needles. Pirate beetles sex consists of stabbing females in the abdomen and injecting sperm into her. Potentialy, a male could inject his rivals with his own sperm and the semen would travel to his gonads. The next time the inseminated male had sex, he would be impregnating his mate with another's genetic material. This kind of reproductive foul play is unlikely to actually occur, but it is possible. Source:"Dr. Tatiana's Sex Advice For All Creation"