Christmas is all about giving and receiving. Especially, we think, when it comes to the bedroom. Few things are more conducive to saucy shenans than a roaring log fire, a glass of mulled wine and some mistletoe to get the ball rolling.

Okay, so trudging home post-shag wearing a Mrs Santa outfit isn't the most glamorous of situations (trust us), but surely Christmas time - with its jokes about stockings, stuffing and crackers - is the perfect time to indulge in some festive hanky-panky?

NO, says psychotherapist Lucy Beresford. NO IT IS NOT. Christmas, she argues, is the time when you're most likely to let your guard down and give your vagina away as freely as some crap, re-gifted toiletries.

Which is something, she says, to be firmly avoided if you're looking for lasting love.

"Picture the scene," she urges. "You've liked a guy for a while now, yet you've had few opportunities to get really close. But suddenly it's party season, and you know you're going to see him socially.

"You're ready for it. You've zhuzhed your hair, selected your outfit, and been practising your 'I've-barely-noticed-you-before-but-I-might-be-interested' body-language (glancing at him then looking away, in case you'd forgotten).

"You pop some condoms into your handbag and…Whoa, slow down. Hit the pause button. Is this what you really want? To give away your vadge for free, like a disposable gift?"

You might be inclined to answer, "Mmm, yes please!" But, Lucy believes, this attitude will leave you lonely come the new year - because she reckons men are after just one thing...

"Let's face it," she says, "guys just want sex. They like nothing better than notching up strokes on the bedpost – and then moving on. And you want to make it easy for them...?

Is this what you really want? To give away your vadge for free, like a disposable gift?

"Come on. You (and only you!) are in control of the sexual fun you can have and how mind-blowing your sex life can be. Ruthlessly respect yourself and your vagina, and the right kind of guys will come running.

"I want people to have great sex, swinging from the chandeliers or getting your man to jump off the wardrobe in a Batman suit [note: this is not how Cosmo personally gets off]. But your priority is to judge whether the guy tonight is interested in you, not just your vagina."

We're totally down with the great sex bit, even if we're not sure about keeping our vaginas locked up like precious flowers and assuming all men are ruled by their penises.

But if you think Lucy's safety-first plan could be for you, here, in her own words, is how to "keep your vagina safe from men who simply don't know any better than to treat it like trash."

1. Love your body.

The more you know how to pleasure yourself, the less you'll feel the need to cop off with a man too soon. Ahead of the party, have a long bath, get soapy with your intimate bits and afterwards, slather on the body lotion. Then masturbate before you leave the house. You'll have brought your libido down a notch or two while entering the party with a compelling, post-sex after-glow

2. Maintain the mystery.

Build up the sexual tension, with a combination of flirty chat and glances while circulating the room. You want him to think you're uber-popular, while at the same time unattainable. Guys love the chase, so hold out the carrot of sexual gratification and make him sing for his supper.

3. Respect your vagina.

By respecting this precious part of your body, you treat yourself with respect too. After all, sex is not a numbers game. It's bigger and better than that. So even though you're experiencing tons of sexual tension, keep a clear head and conduct some subtle research on the night to see if he has other 'attachments' (wife / alcohol / kids) which will stop him putting you first beyond tonight. Treating your vagina as a precious possession means you become much more discerning about who gets to have fun with it - and with you.

Lucy's new book, Happy Relationships: At Home, Work and Play is out now and you can find her tweeting @lucyberesford.

Do you agree with Lucy? Let us know below the line or tweet us @CosmopolitanUK