In personal ads, "sk8" typically refers to "skate," often denoting a person who enjoys Skateboarding or is part of the skateboarding culture. It's a shorthand abbreviation that appeals to like-minded individuals who share similar interests in skating and related lifestyles. This term can also suggest a youthful, adventurous, or alternative vibe in personal profiles.
In the personal ads that I have seen, LOS means Lost or Stolen.
Androgynous
For sex :)
Long Term RelationshipLTR in personal ads means long term relationship.
OHAC mean in Relationship
friends with benefits.
Bareback, or no condom
water sports
In Search Of
professional
Pay to play
"short Message service" in other words text. It's not exclusive to personal ads.