From the Latin 'Lacina videlicet lorum' this word refers to the thin line of pubic hair on the inner vaginal flaps that is always missed while shaving. Specifically it can be located between the labia majora and the labia minora. It has been said to strongly remind one of the classic male 'chin strap' beard.
"So I was going down on my girl last night and damn. I just could not unsee that flapstrap."
"Girl looked like she had an upside down Jason Derulo down there!"
"Girl looked like she had an upside down Jason Derulo down there!"
by Merchants of Fine Muff May 11, 2015