Cap

To bail on someone, ignore them on purpose, or not show up for an event you said you were going to attend.

"Yo dude, I can't come over today I'm sick..."
"Bruh, you're cap as fuck."
"Nigga I'm not capping I'm sick as a dog!"
"Capping ass mother fucker I don't fuck with you anymore bitch."
"You always think I'm capping on you man, the fuck?"