tailpipe
Definitions
General Science
- noun a tube at the back of a motor vehicle from which gases produced by burning petrol are sent out into the atmosphere
Cars & Driving
- noun the last pipe of the exhaust system which fits behind the silencer and extends to the rear of the vehicle
Slang
- noun the anus. A US teenagers’ term. This predictable use of the word (‘exhaust-pipe’ in British English) is possibly influenced by the car driver’s experience of having another driver ‘up one’s tailpipe’, i.e. driving too close.
http://www.dictionarycentral.com/definition/tailpipe.html