The "big bang" is falsifiable.
Ignoring eh!'s unfortunate comments, he is right about the Big Bang theory being falsifiable.
The Big Bang theory makes several predictions. It predicted the cosmic background radiation (CBR), among other things. Not only that, but it predicted what shape
it would take. Note, of course, that this was a prediction based on incomplete data (at the time) and assuming "perfect" conditions, so the initial result was less than perfect. There's a lot of static in the observations, mostly due to, I believe, planets and other large bodies getting in the way, as well as defects in the devices themselves
. Here's an image:
The image on top is the prediction, while the bottom one represents the measurements taken.