To avoid unwanted sex with someone you know, try to avoid provoking moments, which can lead to intimacy. First of all, be careful when frank conversations, especially when discussing your personal problems. At such moments may well be a need for a friendly hug, and physical contact - one of the main factors causing sex.
If you need to be alone with your friend, in any case, do not choose to do their apartment or, especially if the house no one else would. It is better to choose a quiet corner of the park or park where no one will disturb the conversation, but at the same time and excessive convergence will be impossible.
If as a place for the meeting you have chosen a cafe or restaurant, please refrain from alcoholic beverages. Otherwise, after dinner may well be tempted to continue the evening at home one of you, or stay in a hotel.
During the conversation, try to refrain from provocative movements or attitudes against your friend. Even if you're familiar with him since childhood, avoid asking him to fasten the strap of her bra, brush away the speck from the face, etc.
Try not to go with noisy parties. Firstly, most of them associated with alcohol consumption. And secondly, the very atmosphere of such events, dance, ambient lighting, greatly aided by the desire to stay together in some secluded corner.
If you are still left alone with his friend, watch his behavior. If he kept trying to look you in the eye, move up as close as possible, as if inadvertently plays your hair, touching the hand or arm, it says that he does not mind to go beyond friendship. In this case, it is better to straighten it, and if that does not help, then leave. Do not be afraid that it will cause him offense. If he also appreciates your friendship, he should understand.