Ancient Chinese Whorehouse (1994)

A young woman is sold to a brothel by her grandmother. After doing the maths that in her 5 year contract she'll have to sleep with over 5000 men, she decides she'd really rather not. She tries to escape but is caught and tortured by being placed in a tub of eels with her legs clamped open, which is then heated above a fire. That's about as far as I got before turning it off.

Avoid.