A friend who's never played DND before joined my group, and his back story is that a wizard accidentally summoned him from our world. He's literally just a sleazy car salesman, and so far he's talked a bandit chief and priest into buying cars. Cars that don't exist. I can't decide if it's aggravating or hilarious that the rest of the group has decided that his sales-talk is going to be their opening move in every battle.
That is a fantastic backstory and a great idea, one of my party had an idea to create a snake oil rogue and this will serve as good inspiration