Impse

Impse is the "act of copulating with an imp". Impse first appeared in a piece of fan fiction posted in the Doomworld Forums and was popularized further by the joke WAD Imp Encounter.

Impse makes an appearance in many Doom WADs, including Action DOOM, Massmouth 2 and the secrets in Deus Vult.

The name is a play on goatse, a famous shock site.