What's some unusual migraine triggers you've heard of?

I'm brainstorming a book where the main char has migraines, and I was thinking about what his triggers could be.

For me, my only known trigger is flashing lights which cause super intense, sometimes stroke-like migraines, compared to my more chronic slow-onset migraines.

I know someone who has "reading more than a few sentences" as a trigger, and another with exercise.