I pulled a prank in Dr. Richard Feynman's physics class in my sophomore year and to this day I cannot reveal it to a colleague who was also in the classroom as a student. Physical violence might commence if I were to reveal it. And since we both are sandan, we might hurt afterward.
I entered the classroom on the first day to see two of us about 18, four or five others of 20ish and the same number of mid-20 to mid-30 students from China, Korean and India. A very interesting group to say the least. And there was the Dr., dressed like a beach bum, a real one, with torn baggy shorts, some very well worn sandals, a permanently chalk stained teeshirt and hair that looked like he combed it in a previous life. He looked odd at best but he was holding a set of bongo drums, so it looked like a long journey was beginning for this young pup.
As that first day progressed, it was clear that the Dr. had a near diabolical look of someone ready to uncork a great joke, launch a tricky practical joke or pounce on a timid response from us (the stunned listeners). He seemed intent on creating a situation to test each of us. He worried me greatly.
So it was not surprising when he asked a student something that caused the student some discomfort, especially the foreign students who were used to teachers who demanded total respect and classroom decorum.
The stunt. Dr. Feynman would ask a question and if the student was slow, he'd grab his bongos and play the something like the Jeopardy count down tune. Very annoying actually, and disrupted the heck out of the thinking process. If the student did not respond, he thumped them impatiently and finally gave them a thud. And had a disappointed look.
So, not surprisingly one of the Chinese men (about 35) was totally intimidated. You could see his terror and frustration one day when Dr. Feynman asked "Yeung, can you solve this higer order derivative using combinatorial methods." Well an American student would know what that meant but this Chinese man was nearly in tears and Dr. Feynman played something liked Rawhide on his bongos. I was nearly peeing my pants with stifled laughter. The Chinese guy stormed out of the classroom after class and you could see Feynman kinda chuckling.
Next day, I showed up with one of those windup monkeys that beats on some drums and had it fully wound, ready to go. I asked Dr. Feynman to explain why a gluon was not just a type of quark, and not some separately defineable particle. He looked stumped, and as he turned to write on the board, there went the monkey playing his seudo-bongos and since I had just leaned over and put it beside the Chinese guy's desk, Dr. Feynman assumed that the Chinese guy was paying him back for yesterday.
Dr. Feynman stared at it for a moment, looked a Yeung and said, "so you think I'm a stumped monkey, do you?", walked over, picked up the monkey and simply turned to resume showing me how stupid my idea was. The Chinese dude was professing his innocence and looking around like "who did this to me"?
Feynman mentions it in several of his books. On the last day of class, Dr. Feynman always gave out quirky gifts (most hand made) with individual meaning. He gave the Chinese guy a drum stick made from a hard Chinese wood and he gave me a leather monkey with the head un-attached, and he said, "you'll have to glue-on your head". And let out a pretty funny laugh.
I had two more classes with him and he used to stare at me like he was watching for the next trick.