a stoners dozen
A stoner's dozen is 11 because you always eat the twelfth one before you even finish the first one. You’re too high to count, and you’re too lazy to make another one.
I asked for a dozen cookies and got 11 because I ate the last one before I even got stoned.
The baker said it was a stoner’s dozen because I bit the whole thing in half.
My friend said I only brought 11 because I ate the 12th one while I was still on the couch.