Taylor Swift finally denied rumors she played the bear who attacked beau Travis Kelce in "Happy Gilmore 2" -- and turns out, the guy actually behind the costume has a surprise as well ... he had no idea he was acting opposite such a big name!
TMZ caught up with Brandon Alan Smith, the actor who hopped into a bear suit and ambushed a shirtless, honey-slathered TK for the recently released 'HG2' ... and he spoke to us about Taylor's recent praise while admitting he had absolutely no clue he was in the presence of an NFL star, let alone THE Taylor Swift's boyfriend.