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2 definitions by powderhound

 
1.
the occurunce of an unwanted erection during a ride in a car, truck boat, airplane, etc. usually occurs on long trips.
dude, i hope she doesnt see my road bone. I've had it since we left town and i cant get rid of it!
by powderhound February 27, 2010
 
2.
The covering of shit on the bottom of a man's balls, when a girl shits while having sex.
She was so excited to have sex with him, she forgot to use the bathroom, and gave him a chocolate undercarriage.
by Powderhound April 12, 2014