When one farts hard, expecting nothing sinister, and a nasty surprise ensues. This useage arose after the battle of Helm's Deep, which is an thinly-veiled innuendo for an anal cavity.
Victim: Hurry up and get us to Taco Bell... I think i just tossed a dwarf. (Tossing a Dwarf)
Gimli: Nobody tosses a dwarf!