a term used to describe the act when one decides to masturbate, in this circumstance, usually in a inappropriate location.
INT ITALIAN RESTAURANT
John: So here is to Emily and Howard! Two years of marrital bliss!
Peter: Hear hear!
everyone cheers and clash glasses in celebration
mid-meal, everyone is involved in some kind of chatter
Alexander is sitting in the middle of the table, he looks around nervously, he puts his hand into his pocket and starts masturbating slowly and as unnoticably as possible through the material of his pocket
everyone leaving the restaurant
Alexander runs down the street excitedly
Close up of Alexander
Alexander: I just had a Sly Wank!