A Hellen Keller Moment is when you go full retard(never go full retard). When you forget something really simple, or have a "Brain Fart". If you have "selective hearing", that is a good example of this.
Teacher: Jimmy, what is 2+3?
Jimmy:Uuhh, 74.
Teacher: No Jimmy, it's 5.
Jimmy:Sorry teach, I had a Hellen Keller Moment.
2👍 3👎