Red-sided garter snakes have quite an unusual time during mating season. Every spring, tens of thousands of these snakes emerge from hibernation and engage in mating balls (like orgies). The males emerge first, waiting for the females. Whenever a female appears, the males surround her, rolling and writhing until one finally mates with her; but often multiple males will take the opportunity.
Even weirder, is that some of the male snakes can create the same female pheromone (a chemical released to attract males). These are known as “she-male” snakes, and they often fool other males into trying to mate with them. However, the reason for why they do this is still unknown.