A sexual act which is easy to try but difficult to master. The art of flumping involves two people pushing their asses against each other, with one individual farting so that said fart enters into the recipient's anus.
Sometimes known as stuffing rope, or stuffing the marshmallow, the art of flumping is one whereby a male consumes too much alcohol, resulting in his penis resembling that of a marshmallow. He then proceeds to try and fold and push it into the woman's vagina - unsuccessfully.
Eliot - hey man, where'd you go last night?
Stu - went back with that girl.
Eliot - sweet, good night?
Stu - yeah, ended up flumping for 3 hours.