Decorate your cart with ribbons, flowers, etc. Maybe even attach a fake license plate like a kid’s bicycle. You could even change up the wheels and put on some heavy duty ones. If you got a receipt when you bought it, put it in a laminated pouch and keep it handy to pull it out when he gets in your face. (You could always make up a fake one, too.)

He’ll look like a jerk hassling you about a cart that obviously isn’t theirs and I bet you even get some complements on your creativity.

Pray for him. He’s obviously got issues.