I've been stung by this one in Soho.

Pleasant looking bloke in a casual suit walks upto you whilst standing you're outside a pub having a ciggie in the early part of a busy Friday evening.

He goes, "Mate, I need some changing for parking. The machine doesn't take 2 pound coins".

He's showing you a 2 pound coin in his open flat palm.

You hold your beer in one hand, dangling the ciggie on your lip whilst fishing for some coins in your pocket. You then flip a couple of 1 pound coins into his palm with the reasonable expectation he'll hand the 2 pound coin to you.

Nope, he closes his palm and strides off cheerily calling back, "Thanks, Mate". You are left open mouthed.

That has happened to me over the years. Twice!

It won't happen a third. Cut to me this coming Friday night in Soho after a few beers...