Here's one: When ya hit a baseball through a neighbor's closed window, ya start singing "Oops-Eeps."
HA HA HA! That was hillarious!!
Okay... Let me think...
Running a nuclear reactor with the idiocy of Homer Simpson; when your boss comes in, demanding an explanation, you start singing "My Way."
EDIT: Okay, here's another one: When a mob tries to obliterate you, your house, etc. you start singing "Kids Like Us."
EDIT 2: You come back home, and when you see that you have a message on your answering machine, you say, "A message, from Beyond the Mysterious Beyond." (Okay, so that's not so good...)
EDIT 3: When a gang of bullies try to beat you up and take your lunch money - even going so far as to wait for you at the end of your block (where your house is), you say, "Maybe we'll all live together someday."
EDIT 4: When you see a very tall man, trying to start his problem car (i.e., the car that WILL NOT RUN), you say, "Hey Shorty! Need a lift?"
EDIT 5: Upon growing a very large potato - to eat - you start singing the "Family" song. (Trust me, people will not only give you weird looks, you just might get a visit from the nice men with white lab coats!

)
EDIT 6: At a local Jazz club, when it's your turn to play or sing, you sing "Girls and Dads."
"And the Most High said unto Moses, Ahayah-Asher-Ahayah. And he said, Thus shalt thou say to the children of Israel, Ahayah hath sent me unto you... This is my name forever, and this is my memorial unto all generations."
1953-2011... One day, mother, I shall see you again...