come to the dark sides, what’s up with cookies

Am I the only person who doesn’t get the whole “Come to the dark side, we have cookies” thing?
I mean the first two or three times I heard it, it was kinda cute. Not really worth repeating.
But I hear people say it alllll the time, it’s on like 30 different shirts. Why? I just don’t get the why it’s SUCH a popular saying.

Maybe I’m just dumb and I don’t understand it. That’s all I can figure. Or maybe it’s just because I don’t like cookies all that much.