Not me, but some boys at my school spat in a teacher's tea.

We had a school counselor who had a reputation for randomly entering any class to pick a naughty student and take him to her office for interrogation. There she'd threaten him with suspension for something he'd done weeks ago, and his only recourse would be to spy on his classmates, particularly the lovebirds.

This one day, she caught the naughtiest 4–5 kids of the classroom live in action and took them to her cabin. Dire consequences were revealed and while a deal was being brokered, the peon entered the office with a cup of tea and a message from the school's principal, that she wished to see her for a moment. She excused herself and told them not to leave.

Well the counselor had grossly underestimated the virtues of the pack, and they took turns to spit in her tea.

She returned after a few minutes and began to humiliate them while sipping her beverage(not tea anymore). She never came to know that they were not laughing at her jokes.

She was a nasty person, and I wish I could tell her about it after I graduated.