The Irish singer enjoyed a night out at Miami Beach hotspot Taqueria y Tequila on Monday night (10Aug15), and he gave an impromptu performance with his guitar while overlooking the busy bar, according to the New York Daily News.

A source tells the publication, "He got a bottle of Grey Goose (vodka)... he paid for the bottle and tipped very well. Five girls met him on the balcony and he picked up his guitar and serenaded them. Then the crowd below got crazy and tried to get up the spiral staircase, past two security guards, to get a better look at him."

Horan is currently in the U.S. on tour with the boyband.