2. v. to prevent someone from having intercourse.
1b. Are you feeling ok? Where's your head at? You're really cancelling the clown today.
2a. After dinner last night I thought my girlfriend and I were going to have intercourse, instead she cancelled the clown on me.
2b. I was really getting to know that girl through intense conversation and then my douchebag friends intruded on my squirrel and cancelled the clown on me.