There's a theory that the morphology of the glans/coronal ridge acts to displace the semen of other partners. So at one of the HYDRA trash parties, everyone takes turns gang-banging the Winter Soldier until they can't get it up anymore. The last guy to ejaculate inside him wins.

(I'm completely serious, just put "sperm competition in humans" into Google Scholar, there have been all sorts of studies done on this.)