I am the reigning Queen of Elementary School comebacks. Here are a few examples:
"This movie is stupid" comeback: "You're stupid!"
"I hate this stuff" comeback: "I hate you "
You get the gist. It is rather fun, only it doesn't work in some circumstances.
"I'm gonna go eat dinner" comeback: "You're gonna go eat dinner"
You see?
There are many more, but they are hard to define. They are best used at random, so I can't really list them here. Lets try to use immature comebacks at least once this week.