I remember playing in a "B" team exhibition match in college, and, I was playing well, but I didn't realize how well until, when I went to shake my opponents hand on the 11th green, thinking that I beat the guy 9 and 7, he informed me that I had actually beat him 9 and 8 on the 10th green.
It was a bit embarrassing, since he had been thinking for about 10 minutes that I was being an ass, trying to rub in the defeat by not acknowledging the victory, but once everything was explained, we had a cordial afternoon playing out the remaining holes.