At an annual meeting of the Society for Integrative and Comparative Biology, Jonathon Pruitt, a researcher at the University of California, Davis announced that he's found an interesting mating practice among young comb-footed spiders (Anelosimus studiosus). Apparently, the spiders engage in a bit of what Pruitt's calling “sex play,” in which young males of this species participate in practice sex with juvenile females before finally mating.
Pruitt and his team noticed young males drumming their legs and sex organs on the not-quite-mature females' webs, and miming sex with ones that assume the position. This seemed a particularly courageous move, since the young females, who haven't yet fully developed their reproductive system, occasionally complete their instinctive mating ritual—and eat the males.
With more observation, researchers noticed male spiders that practiced sex with immature females had better luck mating in the future. The group believes the speed with which an experienced male beds a mature female allows the male to complete the mating process before another male yanks him off.
We can hear it now. “No, Mom, really! We weren't having sex! We were practicing! Like those spiders!”