The willies are that creepy, uncomfortable feeling you get when something makes your skin crawl or gives you the shivers. When you say something “gives you the willies,” you mean it makes you feel nervous, spooked, or uneasy in a way that's hard to explain.

Maybe an old abandoned house gives you the willies, or the way a spider moves across the wall, or a strange noise in the dark. It's not quite fear and not quite disgust: it's that tingly, jittery sensation that makes you want to look away or leave the room. You might get the willies from a creepy story, a weird dream, or even just thinking about something unsettling.

The word is always plural and it's informal: you'd say it to friends but probably not in a book report. “That horror movie gave me the willies” means it left you feeling creeped out and uncomfortable, even if nothing in it actually scared you. Some people get the willies from harmless things like clowns or dolls, while others need something spooky before they feel that peculiar shivery sensation.