When you are chilling in class and get a boner, particularly for no reason. Usually happens in the same classroom every day; particularly common throughout Jr. High and High School
Spencer: WTF, i always get this random boner in Mrs. Cone's room!

Garrett: Yeah, i get one in that class, too. Carver said that it's called a classroom boner.
by Boner_Man October 20, 2009
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A classroom boner is a spontaneous erection that a guy gets when he's in class.
In aeronautics class today, I got a classroom boner!
by USAF Cadet October 20, 2020
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A classroom boner is the hard-on a guy gets when he's standing to recite something during school.
I got a classroom boner today in English class!
by USAF Cadet September 23, 2020
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