Additionally, the term Big Bang was coined by Fred Hoyle who was sternly denying the theory of an expanding universe that had a beginning. He mocked the theory and dissmissed it as a "big bang".

As more and more evidence suggested that it indeed seems to be true, cosmologists around the world adapted Hoyle's mocking term, as it actually had a catchy cling to it.

So the big bang is actually an ironic name for the phenomenon it theorizes.