A do-over: you hit a bad shot, ignore it, and replay from the same spot with no penalty. Mulligans are pure casual-golf custom — the Rules of Golf don't allow them, so they never appear in tournaments or on rounds posted for handicap. The classic version is the "breakfast ball," a free re-tee on the first hole before you're warmed up. Etiquette tip: it's a gift from your playing partners, not a right — ask, don't announce.