It's one of these days

You know what I mean? No? Well, just read this...

Weirdo: you sex me L$100
Tsai Cheng: 100?
Weirdo: yes
Tsai Cheng: you want 3 minutes of sex?
Weirdo: 20 min(s)
Tsai Cheng: that is 1000/30*20=666L$

Presses her heel against the doorpost and sighs...