The best Geordi moment is in the first season blooper reel. Someone suggests some treknobabble explanation, and Burton blows his line, saying "Oh, I get where you're coming from! We drop-- shit!"
Even Stewart forgets sometimes. He's standing tall, addressing the viewscreen then suddenly blanks, saying what sounds like "Shit! Can't remember the fucking line!" The line was supposed to be "Acknowledge." And Burton had to prompt him.