Masturbating discretely while on public transportation. Often done via pockets in trousers. More daringly, while sitting down, some individuals will even unzip their fly and insert hand into area with the concealment of a bag on lap.
I was on the subway last night and this smoking hot chick sat in front of me. I put my hands in pocket and immediately commenced vigorous commuterbation.
by Royds-McLloyds March 1, 2011