Are you sure it's not BBW - in which case it would be Big Beautiful Woman.
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.
professional
water sports
Pay to play
friends with benefits.
In Search Of
OHAC mean in Relationship
Bareback, or no condom
"short Message service" in other words text. It's not exclusive to personal ads.