I'm seeing the term y in a lot of ads. What is it short for?

Not sure what term you are asking about. I'm not familiar with "y" as a term.

Possibly "ymmv" your milage may vary = you may or may not receive the services the reviewer got.

so I'd suggest checking the urban dictionary.

Swim

No it usually appears to be part of a physical description-example "with a beautiful face and long, y legs that I can't wait to". At first I thought it was an acronym for young but it doesn't fit in many examples.

Maybe it is being used as a superlative as in definition number 9.

END OF MESSAGE

This seems to be the result of a robot removing the character sequence "s e x" wherever found in ads.  Girls often describe themselves as "s e x y" and get left with just "y".   You may notice some other beheaded word remains too; "a s s" gets removed, and probably some others.  

Anybody confirm

END OF MESSAGE

I've researched it out and it seems you're correct. Thanks to and everyone who took the time to answer

pretty sure its the same as saying V or join downtown, loads of peeps say "I went to dine at the Y" you know?

...Dine at the y wasn't his example and his example makes it clear this is something else.