A Prairie, Wis., man was jailed early Wednesday morning after a police officer said he slapped his girlfriend so hard that he could hear it over the roar of Duval Street during Fantasy Fest.
The officer drew his Taser stun gun and ordered the man up against the wall, reports said.
Robert Floreani, 47, smelled of booze and "acted as if he had done nothing wrong" while being questioned by Officer Fred Carter Sims.
Floreani remained in the Key West jail Thursday, held without bond.
Sims was working an off-duty detail in the 200 block of Duval St. for Fantasy Fest and was in uniform at about 12:25 a.m. Wednesday handing a stolen bike report.
As he was speaking to a woman about her missing bike, Sims said he couldn't help but notice a couple yelling and cursing and apparently having a public argument.
A crowd of more than 50 people stopped to stare, Sims said.
The man, wearing only a pair of red plaid boxer briefs, and the woman, in a matching red plaid bikini and boots, made their way down Duval to within 10 feet of the officer.
That's when Sims said the man's open hand came down on the woman, striking her face.
"This hit was so hard, I could hear it over the hundreds of people on Duval Street and the music coming out of the different bars," Sims wrote. "The female was stumbling to her left side, almost falling to the ground."
The man was jailed on misdemeanor disorderly conduct.