PSTS 

Stands for 'Petite Sized Testicle Syndrome'

You coming out tonight Rich?

no mate.

oh my, you have a severe case of PSTS

PSTS by Sandwich & Pingu February 24, 2011

PST's 

Acronym for PURSE STRAP TITTIES. When a Girl wears a Purse and the Purse Strap goes across her chest resulting in accentuated Titties.

Damn, That Chick with the Gucci Purse has got her "PST's" in full effect.

PST's by DJ Carlo July 8, 2005