A match that can only end when one wrestler verbally says 'I quit' into a microphone. No pinfalls, no submissions, no ref stoppage. Just pain until someone breaks. The drama is entirely psychological, it's not about the moves, it's about the breaking point. The Rock vs. Mankind Royal Rumble 1999 is the most famous (and most controversial, they used a recording of Mankind's voice). John Cena has had some of the best modern I Quit matches because his character never gives up.
"The ref is shoving a microphone in his face. 'Do you quit?' 'NEVER!' He just got hit with another chair shot. 'Do you quit?'"