Top definition
An illegitimate boner. An erection received at an inappropriate time i.e. math class or watching football with your boys.
Sometimes this will happen in a car, often while driving to a job site, scientists including myself feel that this is do to the early morning vibrations in the car, or deep seated homosexuality.
Bryan will you come up to the front of the class and do a math problem?
No I've got a bone sac.
by Cole Richards November 28, 2005
Mug icon

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug