An Eagles victory this weekend could be VERY costly for ex-NFL star Bart Scott ... 'cause the former linebacker guaranteed he'd shave off one of his eyebrows if Philly beats the 49ers!!
The 41-year-old made the promise during ESPN's "Get Up" show on Thursday ... saying he's that confident San Francisco will come away with a win over the Eagles on Sunday.
"Can we have a one shot on me and [former NFL player Damien Woody]?" Scott asked during a fiery segment breaking down the Eagles vs.