tenure gap 

The difference in the overall personalities and classroom behavior between teachers (specifically high school teachers) who have received tenure, and those who have not. For example, a teacher without tenure may be overly cautious in class in order to avoid offending anybody in the slightest, whereas a tenured teacher simply couldn't give a shit.

Person 1: "Hey, dude, how do you think our chemistry teacher got away with whipping his dick out in class?"
Person 2: "You know, the tenure gap."

tenure gap by Pleco September 27, 2017