This happened a couple of years ago. I was getting drinks with a few of my classmates after a lab close to the end of the semester. We were all in the same major so got to know eachother pretty well, though often they were awkward with me and would dismiss me because I was a woman. Anyways I was doing the best in this genetics course and they knew it. We were chatting about the exam and I joking told them not to feel bad for getting a worse grade than me which led to so arguing.
Eventually one guy said want to bet on it? Feeling confident I said sure, if I do better to you can write my term paper for a different course that continued into the next semester. They were all hesitant to agree but eventually one guy said, sure but if I didn’t I would have to strip for them. Laughing at the prospect I said sure if you promise to get me an A on that paper. He held out his hand and said sure if you put on a good show for us. We shook hands and eventually the night ended in a hangover.