AAA is what fanboys use to brag about game when they can't use the sales to brag about that game. It's a buzzword, it doesn't mean anything. You say that when you don't have anything to say to obscure the argument.
Also, if we go by the metacritics definition, we have that:
AAA: 90+
AA: 80-90
A : 70-90
B: 60-70
C: 50-60
D: 40-50
E: 30-40
F: 0-30
and that is just ridiculous.
How many cups of darkness have I drank over the years? Even I don't know...