Sacha Baron Cohen is an embarrassing husband.

The 'Dictator' star's wife Isla Fisher is constantly amazed by the gaffes he makes when he meets other celebrities, and she was left particularly red-faced when he confided in Jack Black that his spouse was unhappy with the size of her breasts.

Sacha is famous for his 'mockumentary' comedy movies which have seen him play Kazakh television personality Borat and gay fashion TV presenter Bruno and feature him asking outrageous questions to unwitting individuals.

Isla said: ''I cannot tell you how embarrassing he is in social situations. To him, there's no difference between the awkward gaffes he deliberately makes as a comic, and the terrible faux pas he innocently commits as my husband.''

Explaining she and Sacha had gone to a movie screening, which saw a curvy woman make a long speech before Jack made a shorter address, she continued: ''After the film, Sacha said to Jack, 'Why did you have to make such a short speech? You should have shut up the woman with the big bosoms and said more yourself.' Jack said through gritted teeth, 'That was my mother.'

''Although even that didn't silence Sacha. He told Jack,' Well at least your mother has a fabulous bosom.' And he turned to me and said, 'You've always wanted larger breasts, haven't you Isla?' I wanted the floor to swallow me up.''

Isla - who has two daughters with Sacha - also admitted living with her spouse can be testing because he always brings his comic creations home with him.

She added in an interview with the Daily Mail newspaper: ''Sacha does fully embrace the people he plays and you don't know the half of it when he comes to getting into character.

''I've lived with Borat's handlebar moustache, Bruno's Justin Bieber flick and The Dictator's accusing finger.

''At the moment, I'm having it easy - Sacha is writing so he isn't in character.''