Hogan’s Hangout / MyIconography

Hulk Hogan 's Florida bar honored him on his birthday by throwing an all-day rager ... and the festivities got so large, even Nick -- the WWE legend's son -- popped by!

TMZ Sports is told ... Hogan's Hangout in Clearwater threw a 7 AM to 2 AM party on Monday on what would have been the wrestling icon's 72nd cake day, and droves of Hulkamaniacs showed up to pay their respects. Gallery Launch Gallery Hogan’s Hangout/MyIconography

People clad in red and yellow attire cruised through the doors throughout the afternoon ... and at around 8 PM, Nick stopped in to lead karaoke.

Sitting in the spot his dad used to occupy during the watering hole's open mic nights, Nick got the crowd going -- and at one point, he led a happy birthday sing-along for h

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