“I’ve got big box, yes I do” – what does that mean?

Saw it in the last episode of office. I knew it is supposed to funny but not quite catching it.

I’ve got a big box, yes I do!
I’ve got a big box, how ’bout you!
So awesome. I think Michael was just trying to be a goofball and he didn’t know what he was saying. He was just being goofy. But like a lot of things he says and does, it has another meaning which Oscar picked up on. Being “box” is slang for vagina. Erin was just going along with Michael as she usually does.
“Phyllis is just trying to be a man, while I’m the real deal. Come sit on my lap and there will be no doubt!”

Big Box Meaning

u got a big box

‘Box’ is slang for ‘vagina’. It was quite a funny Office moment!