Actress Jennifer Aniston is pregnant with triplets - for a hilarious new TV commercial with comedian Jimmy Kimmel.

The satirical US commercial for smartwater starts with American Idol host Ryan Seacrest presenting a news story about leaked home security video from Aniston's house, which features the actress taking off a stomach-flattening pad to reveal a bulging belly.

Lifting her shirt to expose her baby bump, she asks her unborn kids: "How are my little triplets doing?."

Kimmel makes an appearance in the video as Aniston's grown-up son in a scene around a backyard swimming pool, which is being filled with bottles of Smartwater.


Aniston is later seen revealing the secret to her picture-perfect hair as she removes a wig to show her 'real' dark locks.

The advert, in which the star also appears to crash a car and hires trainers to lift her up and down during work-out sessions, was designed to poke fun at persistent tabloid rumours suggesting Aniston, who is engaged to Justin Theroux, is pregnant.

Aniston has been a spokesperson for Glaceau Smartwater since 2007.