Fallout: New Vegas/Wang Dang Atomic Tango

Wang Dang Atomic Tango is a quest provided by James Garret in the Atmoic Wrangler (located in Freeside). He needs three additional providers for prostitution services: A suave talker, a sexbot, and a ghoul cowboy.

Sauve Talker
Sandiago is located in the squatter camp in the south-east corner of freeside, just across from Mick and Ralph's. He can be recruited without difficulty. However, choosing him causes a bug with another quest, ../Debt Collector/, where dialog options to talk about the debt might not be available.

You may also speak with Old Ben, located near the gate to the Strip. You need at least 50 speech, or either the Confirmed Bachelor or Black Widow perk.

Ghoul cowboy
The Ghoul cowboy is Beatrix Russel, located in the Old Morman Fort. You will need a barter or speech skill of at least 35 to recruit Beatrix, since other dialog options won't help.

Sexbot
You can obtain a lead about a sexbot from Mick and Ralph. He directs you to Cerulean Robotics; to reach it, head to the intermediate gate in freeside, and take the north west path.