A match with four competitors where the first person to score a pinfall or submission on anyone wins. No tagging, no eliminations (unless specified), just four people trying to be the opportunist who steals the win. The strategy is usually to let two people beat each other up and then swoop in for the pin. Fatal Four-Ways are great for protecting the loser — if four people are in the match, losing doesn't hurt as much because you weren't pinned one-on-one.
"He pinned the champion while the other two were fighting on the outside! New champion via Fatal Four-Way! The champion never even saw it coming."