Cumsitting is sitting in cum. This phenomenon started when a woman in Africa claimed that she had not slept with a man but had become pregnant by unwittingly sitting in a man's spilled seed. Cumsitting itself has deep roots in the cum fetish branch of the homosexualcommunity.
Melanie: How goes the Milky White Throne, Cumsitter?
Josh: My ass is slimy and soft from cumsitting, Melly.
to cum in ones own hand (forming a mit with your hand to prevent drippage) and procede to shake hands with another person. usually performed with random members of society.