A boner you get from looking at an under-age girl.
I was watching Full House when all of the sudden Michelle Tanner gave me an illegal boner.
by MR BOYER October 29, 2008
When you get an erection from an underage girl.
I went to the library and had an illegal boner the whole time because of all the high school girls in their short plaid skirts.

Appropriate response:

Nice.
by LCow October 06, 2008

Free Daily Email

Type your email address below to get our free Urban Word of the Day every morning!

Emails are sent from daily@urbandictionary.com. We'll never spam you.

×