The point where the receiving end (more often female then male) experiences such a high degree of sexual pleasure
their mind goes into a state of severe stupor. In this state they would lose the ability to think clearly and register information such as pain. Often those in the "mind-break" state unconsciously make an ahegaokin
face. It should also be noted that "mind-breaks" happen most frequently during rape
"I must of been doing something right last night, because my girl had a mind break and she looked hilarious."
In japanese pornographic graphic novels, a state female heroines undergo when no longer exhibit thought or logical thinking while having sex.
I read The Great Escape yesterday, and in this volume it totally seemed like Ai Sugimoto was mindbroken. She just wanted more and more, she experienced mindbreak.