A kind of belly that you get after eating a ton of food, where to the point where your belly is like a woman's child in the womb, where the term gets it's name. This fortunately is temporary, considering you shit all of the food away in the end of the process.
Oh god... *buraaap!* I-I think I have ate too much food... got a damn Food baby right now... *urp* I think I should probably let it rest...
After a very large meal, when your stomach bulges a little with food, and you can kinda pretend you're pregnant, but the baby inside is only actually food.
After the five course meal, Jessica's food baby was so large that a guy asked her when she was due.
When a person, typically a thin one, indulges in a large amount of food which makes their stomach stick out from the fullness as if they're pregnant.
In the movie Juno:
Juno: I'm pregnant.
Leah: What? Honest to blog?
Juno: Yeah. Yeah, it's Bleekers.
Leah: It's probably just a food baby. Did you have a big lunch?
Juno: No, this is not a food baby all right?
Taking a huge dump after eating an even bigger meal. Often feels like you have lost a significant amount of weight and often appears as if the bulge in your stomach is gone.
I really had to abort the food baby before my meeting since I ate so much at the IndianBuffet.