Justin Timberlake has joked 'SexyBack' is about a rabbit.

The 36-year-old singer-and-actor claimed he had never been asked about the 2006 single - which features the hook ''I'm bringing sexy back'' - and the lyrics were a reassurance for his neighbour, who he was petsitting for.

Talk show host Stephen Colbert asked Justin if he could ask a ''personal question'' and then said: ''Here's the thing, when you brought the sexy back, where had it gone?''

The 'Social Network' star replied: ''Wow. No one has ever asked me that.

''Sexy was actually just the name of my neighbour's rabbit. You see, they were in Nebraska for the weekend and I was petsitting but they were worried I wouldn't return the rabbit so I wanted to assure them, via song, that I was indeed, bringing Sexy back.''

Meanwhile, Justin's wife, Jessica Biel, previously claimed her husband and their two-year-old son Silas are virtually the ''same person''.

She said: ''[They are] like the same person.

''They like to sit and watch golf together. The only TV that Silas is allowed to watch is the Golf Channel, which is really funny.''

But the 'Sinner' star doesn't want her son to follow in the 'Trolls' star's footsteps musically and become a performer when he is older.

Speaking previously about her plans for her child's future, she said: ''There's one thing I don't want for him. I really don't want him to be a musician.

''I know what you're thinking. Good luck to me, right?

''I watch what Justin goes through and he is at the top of his game. He has access to work with any producer and he can actually get songs on the radio. And, this is from someone who makes great music - he tours and makes it look very easy.

''But he's been working for years and years and years to get to where he is.

''I already have this image of [Silas] as a struggling musician.

''I just want him to be like an engineer or a doctor, something like that.''