Sex friends, f*ck buddies, lovers, the concept has many names... but it comes down to one question. How do you have regular sex with someone if you're not in a relationship with him or her?

We all know that amazing sex is (more often than not) borne of familiarity with your partner. You know where to touch her, she knows where to touch you... and when you get 'it' more than once in a blue moon you're free to experiment a little more.

So how do you unlock this fantasy?

Key number one - Draw the lines

If either of you are looking for a relationship... walk away. Women have a tendency to fool themselves into believing that this is the way to get you to commit. It will always end in tears. So, be sure she doesn't want you to be her boyfriend before you start to walk down this path. Do you really want someone you've been sleeping with in tears on your shoulder?

Key number two - Keep some distance

Don't see each other too often, don't text everyday, don't facebook each other. If you're seeing each other two or three nights a week, are texting/calling daily, and checking out each other on facebook... guess what? You're in a relationship. This person is not your sex friend; she's your girlfriend. Admit it to her, admit it to yourself, and start seeing her outside the bedroom. If you're seeing her this much she WILL be getting attached, even if she's not talking about it.

Key number three - She's not your friend

Don't treat her like a mate. We know she's not your girlfriend... but sex friends should still be treated differently to friends - women have egos after all. You can NOT forget to text back, you can't talk about football, and mentioning other women is absolutely taboo.

Hint: If you HAVE forgotten to text back, a quick message like this will get you back in the good books: "Sorry, works been crazy... but my forgetfulness has absolutely no reflection on how much I want to see you naked".

Feel free to elaborate... but note that my message doesn't say you're looking forward to seeing HER?

Key number four - Be clear

Sticking with the above point; never tell her you're looking forward to seeing her. If it's about sex, keep it about sex. Sending her a text that says 'hey babe, can't wait to see you later... really looking forward to it' blurs those lines for both of you.

Key number five - Enjoy it!

This can actually work... so let your guard down! Remember that this is not the woman who will have your children; she is someone who wants to play as much as you do... so play with her. Send her dirty messages, suggest things you wouldn't normally suggest, and have a great time. Take full advantage of having a sex friend and get down and dirty!

Written by Samantha Leese