A seemingly overcaffeinated McDonald's customer threw a cup of hot coffee on a worker during a heated argument over her order -- and now she's on the run.

The incident, which was video recorded by a witness, occurred Tuesday at a McDonald's restaurant in Buena Vista Township, Michigan. Facebook/Buena Vista Police Department

Check out the footage ... the pissed-off patron kicked things off by complaining to the worker at the counter that her food order had been canceled.

The employee tried to reason with the woman, promising her a full refund after she placed the order using the app -- which was automatically canceled when she failed to pick it up in time.

Soon, the confrontation reached a boiling point after the customer said she wanted to trade in her cup of java for some food.

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