Marshall: Oh, my! Look at that. That means we're in the final hour of the countdown.
Barney: I'm not scared.
Marshall: Then why is your right cheek twitching?
Barney: It's not...
Marshall: Maybe it's because future me slaps future you so hard, it reverberates back to the present, shattering the time-slap continuum.
Barney: [whimpering] Please don't slap me.
Marshall: I'm sorry, what?
Barney: Oh, God! Don't slap me again! I don't want to get slapped again, and the first two times hurt so bad, I don't like it! I don't like it one bit!
Marshall: I thought I ruined it by putting a clock on it, Barney?
Barney: Well, you didn't ruin it. You made it so much worse! I can't eat. I can't sleep. I've lost ten pounds. My suits are wearing me. You know what? I'm outta here.
Marshall: Well, no, no, no. you can't leave.
Barney: Why can't I?! Nowhere in the rules does it say that I have to sit through sort of mental torture! You are allowed to slap my face, Sir, but you are not allowed to slap my mind! Good day!