A grown ass man shows up to a PGA tournament in a bright orange "Tiger" suit in the hopes of cheering on his hero Tiger Woods ... but according to a new lawsuit, something went terribly wrong.
The SUPERFAN -- Jason Goodwin (pictured above) -- claims he got "pre-permission" to wear his spirited costume to the TPC Boston tournament in 2010 ... but once he arrived to the course, one of the golfers flipped out.
Goodwin, who says he had a valid ticket for the event, claims security escorted him off the course after the 1st hole ... because Tiger's playing partner, Angel Cabrera, complained the tiger suit was "too bright and bothersome."
Goodwin filed a small claims lawsuit against the PGA in Boston, insisting his civil rights were "infringed upon" -- and he wants $7150 to make things right.
Goodwin tells TMZ ... he chose the amount because it's the most he's allowed to sue for in small claims court ... adding, "I want to make the point that you can't tell people what to wear."
Calls to the PGA have not been returned.