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
Get the mug
Get a Bone Sac mug for your dog Yasemin.