What you wear in your dreams is very important. While in the pub with my fashion friend last week, she narrated a gruesome piece of night-time mind cinema, in which she'd been assaulted in a handicrafts shop by some girls she was at school with. "The worst part," she explained, "wasn't that I couldn't find the right colour of wool or that they were being so vile to me; it was when I realised I was wearing a horrible, horrible coat. And there was nothing I could do about it. I was saying, 'This isn't my coat, honest,' but they just didn't believe me."

I felt genuine sorrow for her. It's one thing to be accidentally caught looking off-duty by a friend or an ex-friend or even a frenemy – at which point I like to run and hide. Recently, having spotted someone I really, really, completely and absolutely did not want to speak to, I ducked into the nearest shop and found myself surveying a set of power tools alongside a row of very fat and confused-looking middle-aged men.

Anyway, it's quite another thing to be trapped, looking rubbish, inside your own head. That's the sort of scenario that eventually gets you on to lithium and self-help books. Being dressed badly in a dream is something of a leitmotif for all those days when you know you look just as normal as anyone else, but you seem beset by a chorus of in-house voices all telling you from deep within your psyche that you're ugly and a bit lumpy. The only way to make these voices stop sometimes is to pretend you're in fancy dress, I find.

So when I was prepping for a fancy-dress party a few weeks ago, I thought it'd be a cinch. The last time I went to one, I dressed as a Bavarian beermaid (it was a World Cup thing; I went as Germany). I tugged my hair into pinwheel plaits, struggled into micro-shorts lashed on with a pair of my friend's dad's ex-City braces and carried around an inflatable stein all night. "Oh, so you did 'fit' fancy dress," my friend said. "That's not proper fancy dress. You have to do it so it's funny, not just 'fit'."

"In fact, not fit at all," someone else added. "Downright stomach-turning is best."

This is hard advice to hear when you're single. But, getting dressed generally when you're single, in fact, becomes a bit of a minefield. You daren't look ropey for one minute, JUST IN CASE. You worry that spending one more day wearing that cardigan means there's a large chance you'll die in it. And it turns out fancy dress is even more riven with potential pitfalls: you don't want to turn up looking dreadful, in case you ruin your chances with the devastatingly handsome French guy in the corner. But you don't want to turn up in bunny ears and a basque, because then everyone will go, "Oh well, she's clearly single," and the Frenchman might think you're American. What to do?

Thankfully, the theme of this party was "space travel" and the invitation arrived with inspiration pictures sourced from Nasa's archives. The host was not kidding around – well, he was, as he also referred to the invitees as guestronauts, but you know what I mean.

"Bought boilersuit online, going to spraypaint some plastic bottles silver, stick them to a rucksack and create jet-pack," read an email from my friend.

A boilersuit would work, I thought, as long as it was more Flashdance than Slipknot – it could even look chic, and there'd be no chance of being the single person who made too much of an effort because they're a narcissist. (Hem hem.)

"Boilersuit is made for an actual midget," came a follow-up email. "Ridiculously short in torso. I can't even stand up straight. Doing 'fit' instead."

And at that moment, I realised what my costume should be. Something stretchy and vaguely utilitarian, with a hint of disco. A shimmering, glittery gold-and-aluminium-coloured Spandex number by catsuit queen Pam Hogg, so tiny and tensile as to look like Barbie clothing before you fill it with your own corporeal heft. Getting into it was like trying to put a condom on a marrow.

But it fit, and it was "fit". I loved it: the perfect combination of hilarious and hip, without being too showy. It would look as good standing in a corner as it would on the dancefloor; it would even look good if I was being sick in the flowerbed. All that remained to do was to duck back into that hardware store for a sci-fi-style power tool to top it all off…