Robert Downey Jr. is known to many as Iron Man, but it seems he has a more lewd nickname.

Speaking ahead of his Cambridge Union address, the Hollywood star was asked how big his penis was by a student reporter.

'They don't call me throbbing k**b for nothing,' Robert, 49, confidently replied.

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Nickname: Robert Downey Jr. answers question on his manhood at Cambridge University address

The Tab reporter Patrick Brooks said he asked Downey Jr. the question because all of the others seemed rather boring.

'Everyone was quite shocked and his publicist looked quite angry,' Brooks told MailOnline.

A mass of Cambridge University students had lined the block from three o'clock onwards to witness the Hollywood star's address on Friday night.

Promo: The actor is currently in the UK promoting his new film The Judge with Robert Duvall

He arrived into Cambridge via a helicopter from London where he had been promoting his new film The Judge with co-star Robert Duvall.

He follows in a long line of celebrity speakers at the prestigious university, with Alec Baldwin talking to students the week before.

Downey Jr. told the eager students that one of the best things about being a celebrity is always 'getting tables at restaurants'.

Made up? When asked about Scarlett Johannson not having a Black Widow stand alone film, and if he was a feminist, Downey Jr. reportedly responded 'that's all make believe'

But he also seemed to suggest feminism doesn't exist.

The Tab reporter asked the actor: 'Scarlett Johansson has never had her own superhero movie. Would you call yourself a feminist?'

He reportedly responded: 'You b*****d… yeah… that’s all make believe, son.'