Jennifer Aniston is pregnant ... with triplets!

Or at least she is in a new commercial for Smartwater, where the newly-engaged actress makes fun of the constant pregnancy rumors by sporting a big baby bump in some "stolen" security footage.

In the clip she also has an alien son, crashes her car, calls herself "Rachel" and shows off a massive collection of wigs.

This is Jen's second attempt to make a "viral video" with the company -- her last one was called "Jen Aniston Sex Tape" and featured appearances by the Double Rainbow guy, puppies and dancing babies.

What do you think of the spots? Sound off below!