It depends on what is in a
thai massage. Whatever the case, as long as there is protection used, there is no risk. Even if there is a chance of unprotected oral, the risk is low for std transmission. Hand to genital contact (i.e. handjob, mutual masturbation, fondling of the vagina, etc) is no risk. Frottage (body to body grinding or contact) is no risk either. Suckling on the nipples or breasts are no risk either.