Doit has the same meaning as the phrase "Do it" only it has more urgency to it and is more often than not, yelled/shouted/screamed. The same thing goes for writing/typing, only it's in capital letters. It's pronounced the same as if the words "do" and "it" were said separately. The only difference is that it's said rather fast, making it sound like "DEWIT"
Common misspellings: duit, dewit, dooit,
Person A: "Hey man, my parents are gonna be out of town and they're letting me have the mansion all to myself... I was thinking of throwing a rave, but..."
Person B, C, and D: "ZOMG DOIT"
When you hear this (Do it) you should react by loudly shouting the Peter Griffin laugh, and when you say it to someone you should provoke them to burst out in the Peter laugh.
(Optional)
After Laugh you can also shout out shipoopy 3 times