Green’s Dictionary of Slang

of a female, having the line of one’s underwear visible through a tight outer garment.

1989		P. Munro Sl. U.
1993		I. Welsh Trainspotting 27: There’s a set of VPLs (visible panty lines) on the chicky in front ay us.
2006		G. Malkani Londonstani (2007) 65: Samira was askin some other guys whether they reckoned VPL was a turn-off or a turn-on.
2024		J. Meades Empty Wigs (t/s) 119: You’re driving around honing your observational powers you’re going ‘VPL, VPL, VPL, thong, VPL, thong, commando, undisclosed...’ .