Robbie Williams has taught his best friend's five-year-old son to swear.

The Take That singer - who has come under fire for his frequent cursing during the group's 'Progress Live' tour - did some babysitting for Jonathan Wilkes and his wife and took the opportunity to expand little Mickey's vocabulary.

Robbie insists one of his own first words as a child was "f**k" and he thinks parents have more to worry about than the vocabulary used by their kids.

He said: "I was born and raised (for the first three years of my life) in a pub. One of my first words was f**k. And one of my first sentences was, 'Give me a f***ing Harvey Wallbanger please.' (FYI I didn't get one).

"Johnny and Nicky Wilkes let me babysit once with little Mickey. I taught him a game called, 'It's the s**t'. It involved throwing a sock over the balcony and shouting 'It's the s**t' every time it landed. They weren't happy. (sic)"

Robbie - who recently admitted he wants to start a family with wife Ayda Field - is unsure what he will think if he ever hears his own kids swearing.

In a posting on his blog, he added: "I wonder what I'll think when my Little Ones ask to watch Dora the f***king Explorer and Ayda looks at me shaking her head."