I'm far from "posh", but I seem to have a habit of making a bit of a nob of myself whenever I talk to anyone who works in a typical "bloke" job. any kind of interaction with tradesman, and I channel my inner-dickhead.
I took my car in to have its alloys redone this morning. I was waiting for the mechanic guy to turn up, and when he did, I introduced myself, and he held out his hand. I couldn't decide whether he was going to shake my hand or take the key, so I reached out mine, put the key in his hand, and shook his hand in one gesture, like I was tipping him a car or something.
The look of "wtf" on his face is going to pop in to my head and taunt me occasionally for years to come.