Not one of the stupidest things I did, but one of the dumbest things I ever said.
I was talking to a girl at the bar and I asked her what she did for a living. she said " I am a Special Ed Teacher" to which I replied “oh, I love gym class.” Then after I realized what I said, the words “I am so retarded” came out of my mouth. Needless to say, it didn’t work out