The visible outline of a girl's thong. Usually seen under her leggings. Many girls wear thongs to avoid panty lines, only to get thong lines instead. Slightly harder to notice compared to panty lines, but ultimately just as obvious. Most guys notice them, but say nothing. Instead they take pictures and upload them online. Just google "Thong Line."
Girl 1:"Look at that girl wearing those cute black leggings!"
Girl 2:"Yeah, but look at her thong lines, how gross!"
Girl 1:"She probably thinks nobody can seem them."
Girl 2:"Yeah, but look at her thong lines, how gross!"
Girl 1:"She probably thinks nobody can seem them."
by Nintenda April 25, 2016
Get the thong linemug.