I've seen this in a few posts but have no clue what it stands for...
Big Name Trainer. As opposed to No Name Trainer or Local Big Name Trainer. Or my personal favorite, Jack Assed Wannabe.
Life would be infinitely better if pinatas suddenly appeared throughout the day.
Big Name Trainer.
then there is BNR = Big Name Rider
Variations on the theme
MNT, or LNT or NNT - Medium, Little and No!