subterfuge snap
A discreetly taken photograph of a complete stranger, usually with the intention of sending it to your mates for their input.
Text conversation:
Dave: Bro, I'm on the train sitting opposite from this smoking hot babe.
Alan: Grab me a subterfuge snap so I can check her out.
Dave: Bro, I'm on the train sitting opposite from this smoking hot babe.
Alan: Grab me a subterfuge snap so I can check her out.