Go visit the many brothels in Geylang - pretty much walk each of the streets on the even number side (from Lor 2 to Lor 20) and explore each of the shops.

You won't be able to miss which ones are the shops as they'll have bright neon lighting or bold street numbers or a guy/girl at the front trying to get you to go in and have a look.

No harm in looking as it's like a fishbowl set up where upon entry, all the available girls are sitting right in front of you in the foyer.

Cheap as hell too... Thai girls are $50/30min, Viets are up to $80/30min and Chinese are the "premium" at $100/30min. Longer bookings are also possible.

Enjoy!