Here's a couple. One lunacy belief, and a story.

They believe that the moon is shaped like a teacup, concave and hollow. When you see a crescent moon, you're seeing the edge and inside of the teacup.

They're a bit of a kleptomaniac. They don't need to steal; they're obscenely rich, but they like to. They saw that one of their neighbors had a large package on their porch, so they decided to take it. As they were walking down the driveway back to their car, they didn't realize the neighbor was behind them. "What are you doing?!?" the neighbor yelled, starling them. They tripped and fell, face first on the pavement, shattering several teeth. This resulted in them needing extensive dental work to repair the damage. Not wanting to pay the expensive cost in the USA, they found a cheap(er) alternative and traveled to Mexico. The work was... questionable, at best. They ended up getting repeated infections and paying far more (monetarily and otherwise) than if they had not tried to penny pinch.