Y Chromosome
The genetic material that transmits the information necessary to make a male. The Y chromosome can be found in one-half of the man's sperm cells. When an X and a Y chromosome combine, the baby will be a boy. See also X Chromosome.
YAG
Slang for gay.
Yeast Infection
A fungal infection of the vagina.

YMMV

Your Milage May Vary. The amount of value you get for your money with an escort can change depending on her mood, or how she feels about a customer.

YMMV Girl A provider who is known for being inconsistent in her attitude and service. i.e. Gets hot and cold reviews.