When you're trying to get it in with a lady, and it's suddenly time to go ( because your ride is here/ the place closes/ it's time for her to leave etc. ) and you end up never getting to do anything with her.
Girl: I so wanna fuck you right now!
You: oh baby, let's do it!
Girl: Oh shit my moms here to pick me up, I gotta go!
Your friend: Well shit dude, Id say you just got clockblocked!
When a friend of yours eagerly brags about how some girl he's talking to agrees to blow him. Curious you ask to see what she looks like, and to your horror she's the most ugliest bitch you've ever seen. Despite your attempts to convince him she's ugly, he insists shes pretty hot. Later when he meets up to get blowed, he soon finds out you were right all along, and she is an ugly piece of shit. He was blinded by the BJ.
Your friend: Yo dude this chick I'm talking to said shed blow me man!
You: Oh nice man lemme she what she looks like!
You: ....ah what the fuck dude she's straight up ugly!
Your friend: Nah man Shes hot...you trippin!
You: alright.. Whatever you say...
Your friend: dude! Why didn't you tell me that chick was