The panty-hate phenomenon is real; I'm just not part of it. That might be because I'm a man, (or, you know, a dude). Based on what I've read as well as independent research, women don't seem to like saying or hearing the word "panties," while men remain indifferent, perhaps because they become instantly distracted whenever they hear it, for some reason.
What it is:
Underwear for ladies and girls. Not much else I can say about it. If you didn't know what panties were, I'm really sorry that you had to learn it from me. Really sorry.
Use it in an Awful Sentence:
"Your sister and mother are at the mall, shopping for panties."
What it Actually Calls to Mind:
An irritating piece of slang that horrible people would use to describe someone who was acting prissy or cranky. Like, you know how the most annoying character in a sitcom set in an office always accuses someone who's pissed off as having "a case of the Mondays?" If you came to work very irritable, that same person would say "Ooh, call the doctor, it looks like Johnson over here has come down with a case of The Panties, heh heh. Hope it's not contagious, or else we'll have a panty-demic on our hands!"
I sure do hate you, Guy-I-Just-Invented.