If you want to avoid heated arguments, never discuss religion, politics, or whether the toilet paper roll should go over or under.

The line plays on the familiar etiquette rule that certain topics—religion and politics—are perennial triggers for conflict in polite conversation. By adding the seemingly trivial question of whether a toilet paper roll should hang “over” or “under,” the quote humorously suggests that people can become just as dogmatic about everyday preferences as they do about ideology. The joke works because it collapses the distance between the profound and the petty, implying that argument is often less about the stakes of an issue than about identity, certainty, and the pleasure of being right. It also functions as a light social warning: harmony sometimes depends on choosing which disagreements to leave untouched.