Ahhh, I so love making fun of Michael Bay, I mean he makes it so damn easy! Oh, here's my previous Bay joke: http://brinkscartoons.blogspot.com.au/2011/12/dont-bother.html
This idea is another example of one of those ideas where I get the basic joke fairly early, but it takes me ages to figure out exactly how to do it. In fact, even the initial sketch I did looks completely different than the final product. It had Michael Bay sitting in between the couple looking quite pleased with himself and the husband was facepalming and thinking something like: "Why did I get Michael Bay to film our birthing video?". But in the end I decided to streamline it more and just have the couple and one speech bubble.
The joke was always going to have the "Is that an explosion coming out of my vagina?" line in it, as that was always the initial idea I had. But in the beginning it was Michael Bay's own child's birth, but that ended up getting too complicated, especially as I had no idea how to get across that it was Michael Bay. So it did take quite a lot of refining here and there for this one, but I glad I finally go it out in the end.