One McDonald’s customer learned a tough lesson: DO NOT try to steal from the soda machine, and definitely don’t pick a fight with employees, ’cause ya might get your ass mopped.

A video posted Wednesday night shows a young lady getting into a blowout with 2 staffers at an undisclosed McDonald’s — and it’s one of the worst ass beatings we’ve ever seen. One much taller staffer tossed the customer like a rag doll … literally.

Hair is pulled, faces are smashed, boobs pop out — and all of that happened to the customer. Spoiler alert: David doesn’t beat Goliath this time.

BTW, the person who shot the video says this was all over the customer attempting to use a water cup to sneak soda from the fountain machine.