Even after defying the rules of logic it still doesn't make sense. First of all, not having two cookies isn't the same as having negative two cookies, but I'll play along and change it to I owe two cookies. If my friend owes four cookies and gives me the cookies that he owes, then I now owe six cookies, not have four cookies. To make this work, he would have to take away from me a debt of four cookies, which would make perfect sense if cookie were to exist, and is no longer funny.
And multiplying debt just doesn't make sense in the first place. It has to make some degree of sense to be funny.
Sitcom? Where? What? Why? What? How? What? Are you talking about your Flash animations?
Well, good job for trying.
http://en.wikipedia.org/wiki/List_of_paradoxe s
There's a list of math paradoxes here.
http://en.wikipedia.org/wiki/Unexpected_hangi ng_paradox
This one is a logic paradox, but I find it highly amusing. It tickled my brain. My brain giggled.