Does the following sentense has any special meaning?
"I'd forgotten what popcorn without cats hair in it tasted like."
Thank you very much.
No specific special meaning no! My best guess in this context would be that the person speaking owns a cat, so normally everything in their house/apartment is covered in cat hair (a problem all cat owners will identify with!).
Presumably, he/she sometimes makes popcorn at home and finds cat (or cat's or even cats') hair in it. He/she is now eating popcorn, probably from somewhere else, which doesn't contain the fur! So he/she is commenting that he/she had almost forgotten the taste of popcorn that doesn't contain cat hair.