The Detroit Lions fan on the receiving end of a punch from Pittsburgh Steelers star DK Metcalf is speaking out ... insisting he simply called the player by his full name before the incident -- but DK is reportedly claiming something much worse was said.
The Detroit Free Press found the man in the stands after everything went down on Sunday ... and he told the outlet he was "a little shocked" by what happened.
"He doesn't like his government name. I called him that and then he grabbed me and ripped my shirt.