RULE: The limit of the willing suspension of disbelief for a given element is directly proportional to how corny the element is, as long as the writer knows it's corny.
Think about it: How many times has some character pulled a cheap pun or trick for the sake of humor? In this way, the Rule of Corny is related to the Rule of Funny, where reality can take a rain check if a certain element is too hilarious to fail.
Our project, entitled "CIA", meddles with the Rule, because the movie is about cookies. What's the name? "Cookie Intelligence Agency." Groan.
What about the beginning to CSI: Miami? "We've got a serial killer who murders his victims based on puns!" "I guess our suspect isn't... *sunglasses*... clowning around." YEAHHHHHHH! (Groan.)
In conclusion, corniness can work if it's conscious corniness. Otherwise, you look stupid. You are stupid. Puns are stupid. But they're so fun. They're pun-sational. Kill me.