There is one thing I would break up over, and that is if she caught me with another woman. I wouldn't stand for that.

Framed as a mock “deal-breaker,” the line flips the expected moral logic of infidelity. Instead of condemning cheating as a betrayal of the partner, the speaker centers his own pride and inconvenience—he can tolerate wrongdoing so long as it remains undiscovered, but cannot “stand” being caught. The humor comes from this brazen self-absorption and the deadpan insistence on a warped principle. In Steve Martin’s comic persona, such lines satirize macho entitlement and the way people rationalize bad behavior by treating consequences (embarrassment, exposure) as worse than the act itself.