What scams have you experienced that made you laugh?

I don't think I'm a good liar, so sometimes, if I deliberately set up some small pranks and scams, I can't help laughing soon, so that people around me can see through my scams quickly and correctly.

I still remember that once in our big class, many people had a water-saving class together, so everyone was in a daze and probably didn't fully wake up after class. My roommate is a person who pays more attention to hygiene, so she brings a thermos cup to class every class, but I forgot to take it in that class, so I sat behind her, so I saw that she didn't take it, and I took it for her when I left. But I didn't tell him.

Back in the dormitory, I thought you and my roommate would soon find that their water cups were gone, and then watch him worry. But who knows that she didn't realize that her cup was missing at all? I waited there for hours, and finally I couldn't hold on. I took the initiative to start chatting up. I said why you didn't drink water today, and then she subconsciously looked for her cup and found it missing. I'm already nervous.

Then she began to think about it, knowing that it was going to be brought to the big classroom, and by the way, did we bring it back to her? We all shook our heads in denial. Actually, this cup is on the desk of one of my roommates, but I can't stand it. My roommate got suspicious and came to my desk to look for it, but he couldn't find it. Then he went to ask the teacher to borrow the key to open the door, and I couldn't help laughing again. Finally, I told her the cup.

I think I just can't help it when people finally really believe this scam, so I have never completely succeeded in a scam.