During WW2 it's common knowledge that solders would drop grenades in the man hole or hatch of a tank to kill the solders inside, however the german sausage drop is a lesser known tactic. The german sausage drop is when a solder takes a shit or throws shit into the hatch of a german tank in an attempt to literally gas them out.

A casual invitation / threat used by an individual that is not afraid of fucking someone up.