(CNN) A college football fan who held up a sign on national TV asking for beer money has raised more than $1 million -- and he's giving it to a children's hospital.

Carson King's sign said "Busch Light Supply Needs Replenished," and included his Venmo username.

He displayed it on September 14, during ESPN's "College GameDay," broadcasting from Ames, Iowa, ahead of the matchup between the Iowa Hawkeyes and the Iowa State Cyclones.

His phone immediately blew up with notifications from Venmo, King told CNN. Within 30 minutes, the 24-year-old had raised $400.

"I didn't think I would make anything, it all started as a joke," he said.

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