What does JACK have up our sleeves?

Here's a clue:

It's bigger than a Breadbox and comes in pairs.

Also, you find it in a sack, but it's also a slang.

What the heck are we talking about?

Stand by, next week we'll have a very big announcement that will make your November bright.

And no, we are not going to be playing all Christmas music.

...or are we?