It was the novelty fashion item of 2012 - but now it has emerged that the Deputy Prime Minister owns one, the onesie has definitely made it mainstream.
Nick Clegg had been answering questions from the public on radio station LBC when he made the bizarre on-air confession.
The Deputy PM faced a series of difficult questions during the morning radio phone-in, but it was his admission over the unusual clothing item which was most unexpected.
The 'onesie', an all-in-one casual suit previously worn only by toddlers, became an unlikely fashion hit at the end of last year.
The Lib Dem leader admitted that he owns one too - although he is yet to try it on yet.
At the end of the weekly 'Call Clegg' phone-in on London's LBC 97.3 radio, he was asked by Harry, from Sheffield, if he had ever worn a onesie.
The Deputy PM responded: "I was actually given a big green onesie in Sheffield, which I have kept in its packaging, but I haven't worn it yet."
Asked by radio host Nick Ferrari if would wear it in public for charity, he added: "It's almost certainly something I would do in the privacy of my own home."
Although credit is due to Mr Clegg for making the confession, political commentators said his on-air confession 'opened him up to ridicule'.
The incident even drew comparisons with former Prime Minister John Major, who it was embarrassingly claimed used to tuck his shirt into his underpants.
Alex Stevenson, deputy editor of politics.co.uk, said: "Any politician who thinks mentioning his underwear on air is a good idea must be slightly crazy.
"Nick Clegg was put on the spot and should get some kudos for owning up, but admitting you own a onesie - even if you haven't worn it - is only going to open you up to ridicule.
"Now, in addition to voters remembering his broken promises on tuition fees, they will now have the mental image of him wearing preposterous underwear.
"Look what happened to John Major after he admitted he tucked his shirt into his underpants - not his most prime ministerial moment.
"If I were Clegg right now I'd be wanting to turn back the clock and take that question again."