Remember the USFL?
The upstart spring football league started in 1983, with impressive crowds and solid television ratings. The league even signed three straight Heisman Trophy winners away from the NFL.
Complete coverage of the Philadelphia Eagles and their NFL rivals from NBC Sports Philadelphia.
When the league looked to expand shortly after, a real estate tycoon turned future president decided to join in.
That's right, Donald Trump became the owner of the New Jersey Generals.
And the league went south from there.
Mike Tollin, director of "Small Potatoes: Who Killed the USFL," part of ESPN's 30 for 30 documentary series, said Trump played a big part in the league's downfall.
Tollin appeared on Philly Sports Talk Thursday and looked back on his time making the documentary, which included an interview with Trump.
In short, it didn't go well.
When Tollin finished a rough cut of the documentary, he sent a copy for Trump to review.
Check out the video above to see Trump's incendiary response that ended with, "P.S. You are a loser."