It is supposed to allow you to use either SHIFT, CTRL, ALT and the Windows logo by pressing one key, but people I know refer it to some awesome joke, as they yell "STICKYKEYS!" in random places and at random times.
Random person: "Um, hi?"
Sticky Keys Guy: "YAAAAAAAAAAAY"
Random Person: "Hello?
Sticky Keys Guy: "I LOOOOOVE STIIIICKYKEEEEEYS"
Random Person: "Sigh..."
2. an annoying default feature of Microsoft where if you press Shift five times, a popup asking whether you want to enable StickyKeys, ruining any streak you have if you're playing an FPS. Can be used to annoy random people
Person 2: Press Shift 5 times right when an enemy sees you to get a quick armor boost
Person 1: Thanks, man. You're my god!
Person 1: WTF IS THIS SHIT NO I DONT WANT STICKY KEYS WTF STUPID MICROSOFT!!!!!!! NOOOOOOO I DIED!!!!!!!!! WTF YOU HACKER!!!!!!!
Girl: What's that ?
You: Have you never heard of sticky keys ?
Girl: Ohhh sorry just thought you left your phone in your pocket. Love you too !