New clip shows Jen sporting a rather large bump

Newly-engaged Jennifer Aniston is showing off a gigantic baby belly.

However, fiancé Justin Theroux can calm down – it’s all part of Jen‘s latest viral ad campaign for American company Smartwater

The video sees Jen, 43, relaxing in spoof footage which is set-up to look like real shots stolen from her home security cameras.

Arriving back after a tough day at work, the actress lifts up her T-shirt and removes a thick belt to reveal an enormous bump, before swigging from a bottle of the water she is promoting.

Jen then pats her huge stomach while asking, “How are my little triplets doing? You must be so thirsty.”  

This isn’t the first time the Friends star has poked fun at herself in a hilarious Smartwater ad campaign.

Last year a comedy video for the drinks company called Jennifer Aniston Sex Tape sent the world into a mad frenzy, notching up 2 million views in just a few days.

SEE PICTURES Jennifer Aniston Style File

SEE PICTURES Celebrity hair: Jennifer Aniston‘s styles over the years

SEE PICTURES Jennifer Aniston goes topless for perfume ad

Rachel McGrath