In "Homer Goes to College," Homer gleefully sets his high school diploma aflame, while singing, "I am so smart, I am so smart, S-M-R-T, I mean S-M-A-R-T!" Behind him his living room is going up in flames.
The now legendary "S-M-R-T" line was actually not in the script and was a genuine error by voice actor Dan Castellaneta. However, the error was so much in Homer's character that they chose to include it in the finished product.
People now chant either "S-M-R-T" or "I am so smart, S-M-R-T", particularly when they're feeling stupid, celebratory, or both.
Homer confidentally talking about his toy-rocket. This may refer to the people who confidently predicted that the Titanic was 'unsinkable'.
"The word unblowuppable is thrown around a lot these days, but I think I can say for certain that... (Boom)".