I attended a university-based martial arts class in the late 1990s. A somewhat-elderly Asian lady (probably mid-50's) began attending classes and progressing through the ranks. She was kind of. . . well, a goofball. Transgressive sort of humor. Made jokes about people's girlfriends. Laughed through demos.

The only time I saw her utterly serious is when the instructor showed off some knife-defense techniques he learned at a seminar. She got a weird look on her face at the overly-styled techniques we were being show and very clearly said, "We did it like this in Cambodia." She grabbed the rubber knife from the sensei, seemingly teleported behind his back, clamped a hand over his mouth, and drew the knife across his throat. "So they no hear any noise," she explained. As a bunch of 20-something kids, we looked on in horror. She seemed to remember herself and looked embarrassed. Left early from class and never came back.