To call it an early night and bail on your friends by yourself before the party or event reaches its entertainment climax.
Butters: "Guys, I'm getting pretty tired, I think I'm gonna call it a night."
The Coon and Friends: "Don't Marcus Out dude it's only 9:15 pm and more girls are coming in 30 minutes. Stay for a couple more drinks."
Butters: "Nope, I'm going home."