In species where there exists intense competition among males for females, we often see elaborate modification to what we would consider normal courtship to increase an individuals' chance of a successful copulation.
A peculiar example of this is seen in the solitary larval endoparasitoid of the cabbage white butterfly. The male parasite, Cotesia rubecula, displays post-copulatory female mimicry in the hopes of copulating with a desired female with whom he and another male are competing.
When the female is ready to mate, she exhibits a characteristic colulatory position by lowering her antenna (see graphic, Figure 2). This serves as a signal to males that she is ready to mate. If two males are present and competing for the same receptive female, it is not uncommon for "male one" to trick the other by assuming the same pre-colulatory pose. "Male two," confused and randy, may attempt to copulate with guised male one. Male one quickly unveils his identity by quickly scurrying over to the female and copulating with her, leaving a disapointed male two in his dust.
Though I have never observed this mating strategy among humans - and I can't say I think it would result in a sucessful copulation - it's a pretty clever behavior adaptation in a competitive intra-sexual environment.
Published in Animal Behavior