This is when a man cannot achieve an erection, so he fakes it by attaching to his flaccid shaft some sort of hard object (e.g. a dildo, marker, phallic-shaped sheet rock), using some sort of adhesive (e.g. duct tape, electrical tape, peanut butter). Generally, sex with a woman will follow.
Etymology: "Florida", a place where old folks go to retire; "Hard-on", an erection.
I couldn't get it up last night, so I pulled a Florida Hard-on.