Police said Steven Tryon, 18, walked up to an Indiana stand where kids were selling Styrofoam cups of the sour stuff for 50 cents.
That's when he demanded the money.
He grabbed the loot - $17.50 - from a girl's hand and ran off.
But the young entrepreneurs were not deterred, chasing after Tryon while calling police.
"I didn't think anyone would come up to a lemonade stand and steal money,'' 12-year-old Fred Erskin told WTHI. "That's really low.''
That won't stop the kids from selling lemonade - they'll just bring a parent along.