The would-be robber at the Chase Bank branch, inconspicuous except for a tie-dyed shirt, "waited in line and handed the teller the (demand) note when it was his turn," said Miramar police spokeswoman Tania Rues.
He apparently tired of waiting and walked out of the bank, where police took him into custody, The Miami Herald reported Tuesday.
He "didn't leave with a penny," Rues said.
Nearby Miramar Parkway was closed and Perry Elementary School was locked down for a short time, WSVN-TV, Miami, reported.
The unnamed man did not show a weapon during the robbery. Police and the FBI are investigating, the South Florida Sun Sentinel reported.