LS- is short for Lichen sclerosus (aka lichen sclerosis or lichen sclerosis et atrophicus) is a painful skin condition that typically affects the vulva (or penis) and anus. In women, LS falls under the general category of vulvodynia (chronic vulvar pain). It is not a contagious condition.
"Oh yeah, she has got LS"
"She's got what?"
"Lichen Sclerosis"
The current crop of misogynist politicians consider any prescription for birth control pills to be little more than a slut license, in effect giving young women permission to be promiscuous.