Cherchez La Femme

 is a perk in Fallout: New Vegas.

This perk gives female characters increased damage on other female targets, and unlocks unique dialogue options for members of the same sex.

Additional dialogue options
This perk can be used to convince the Omerta receptionist in Gomorrah to talk about the Family during the fourth part of the quest The House Always Wins.

You can flirt with Corporal Betsy in Camp McCarran.

You can respond to Rose of Sharon Cassidy's comment about not liking "soft men" by saying that they're rarely a problem for the you. Cass will respond by nervously saying that when she's had enough to drink, she doesn't care who she ends up in bed with.

Behind the scenes
"Cherchez La Femme" is a French idiom which translates literally as "search for the woman" and can be understood best as meaning when a man has a problem, there is surely a woman at the source.