Exaggeration is a device in humor. On the other hand, you need to care about believably in writing, especially in fiction writing.
For example, I'm writing a story where the main character goes to her university to find out about a weird topic. She is laughed at in class. And later in a lab. After this, she becomes a source of gossip--her schoolmates start calling her a nickname and many people she meets later on recognizes her:
"Yeah," De-Shi said. "She's very enthusiastic about animal suicide. You should've seen the little commotion she caused in the department."
"Oh," Cath covered her mouth, "she's Hanging Pup."
"Yup, the very one," I blurted back. I had no idea my fame had spread so far.
This, obviously, is unlikely to happen in real life; I just wrote it for comedic purposes.
The thing that worries me is that some of my readers pointed out that believability issue--so I'm confused. Can you sacrifice believability for the sake of humor at times? If so, what are the limits?