When a male finds a partner (usually a cheap hooker) and takes them to a motel/hotel and rents a room on the top floor. They proceed to have sex, and during sex, the man secretly inches over towards the window while still having sex. He then places the girl belly down in the open window frame and does her "doggystyle". When he is ready to finish, he speeds up, splooges, then quickly pushes her out the window. It is favored by many because it allows you to finish inside your partner and not have to pay a single penny, but do this act with caution, as it IS MURDER.
Bob: "Dude did you hear that Bill accidentally Hump and Dump
Jim: "Yeah, that sucks! They were going to get married!"