AcmeShorts

The ass-shaped robot was a sad thing. It was shunned by the other robots. They all treated it as humans might an inbred backwoods cousin.
It's chief failure as a robot was its unfortunately positioned exhaust vent between the cheek shaped modules. This vent would jettison sulphur tinged steam and unused bits of dried fuel particles at various times during the day, usually when other robots were nearby. Often it would jettison particles and sulphur gas in crowded freight lifts.
To make things worse, dried excess fuel particles would sometimes cake up on the metal around the ass-shaped robot's exhaust vent. When steam would vent, these "piles" would flake off, pulling bits of corroded metal with them, This caused the ass-shaped robot's sensors to become very irritated, and the only way it could relieve itself would be to back up against a corner and scrape the tiny chunks off its cheek modules.
The ass-shaped robot was a miserable thing, and would have wheeled itself into the nearest melting pot, if not for its only friend; the Tonguedroid.