Limits

Kathy: Eric, entertain me.
Eric: [lounging on Kathy's bed] It's hard to entertain you when you're doing a pset.
Sharmin: [brightly] You could run around in circles, that would be amusing.
Kathy: Yeah, that would  be amusing.
Eric: I'm not running in circles, you run in circles.
Sharmin: [tries to run in a circle, realizes there isn't enough space] Running in circles is hard. [begins to spinning] I could spin, that's like the limit of running in circles as r goes to zero!
Kathy: Ok, I'm not entertained anymore.