Own Goal.
The TLN mentions it's being a Soccer term, but neglects the details.
for those unaware, an Own Goal, in Soccer, is when you score a goal against your own team.
In other words... you kick the ball through the goal at the other side of the field from where you should.
Apparently this happens often enough for an actual term to be accepted for it.
It's a rather embarrassing thing to do.
I... did this once.
Back in high school, some 40+ years ago.
Was playing defense.
Tried to deflect an incoming ball away from the goal, and instead only deflected it just enough to slip past the goalie.
The only goal I ever made playing Soccer, was against my own team.
So, the chappie in the story was correct in more ways than he thought in being mad at his name being mispronounced.