Friends with benefits?

This is the time where you have a mature talk with him. Tell him your true feelings and what you want out of this. Make it clear taht this is to be a sex-only fling. Also make it clear that what happens between you is STRICTLY PRIVATE and no bragging to his friends is allowed. Monitor his words and his body language carefully. If he's fidgety or studders his words, beware. But do not judge too quickly, it's not everyday a young man has a beautiful women tell him straight up how it's going to be(never happened in my youth *sob*). Just flat out tell him what you want and be confident about it. He shouldn't reject you. But do be careful, pregnancy and disease will cripple you. Other than that, I wish the best for you and praise you for your willingness to explore your sexuality. Thumbs up for asking first before jumping into it.

If you have doubt, don't do it.

Have a talk with him. Tell him you are interested, but confidentiality if critical for you and you aren't sure you trust him because of what he talked about with his past girlfriends.

Most of us have a very young conversation about sex. By talking to him about your expectations including what is it both of you want from the relationship is elevating that conversation.

If his answers aren't what you want then don't do it. If they are then have fun.

No matter how nice you ask for confidentially, he'll talk cause he's a talker and bragger!!
What is it that he's doing that's bringing more meaning into your relationship everyday since he's always talking about sex?? Since he's told you everything about his previous two conquests, and you've only started hanging out with him, I'd say you can't trust him to keep quiet. I have no idea how you can tell him you wanna be # 3 and asking him to not broadcast it because he'll tell you, "no problem! I'd never tell anyone what you and I do in private I promise!"... that is until you break up with him. His having sex with you will be the same as it was with the previous ones.

I wouldn't do it. You posted this a month ago, and hopefully you've not done it. Not to say that you shouldn't have sex, but unless you can trust this person to keep his mouth shut, expect him to kiss and tell. Girl to girl, I honestly think he just wants to get into your pants and drop you like a bad habit. Unless you two have been really good friends for a while or something like that and you trust each other, then this is more like a hook-up. Be careful hooking up with people at your own school. News travels so fast, it's UNREAL.

If you sincerely like him, make sure he feels the same about you. Also, if you really like him, remember that the 'friends with benefits' set-up is designed to let you have sex with someone (discretely!) WITHOUT the stress of being in a committed relationship. If you're looking for a relationship, becoming his FWB is not the way to do it. Find a guy that genuinely cares about you, not this dude. Because it really sounds like a wham-bam thank you ma'am situation coming on.

Nest time he brings up something about sex - prolong the conversation.
Join in - tell him something about what you've done, or just generally talk about it. he'll pick up the idea that it's okay to talk to you about it - and start to think maybe you want more.
Don't get into anything if you're not sure though.
If things getting out is that big of a deal for you - you have to decided how much you can trust this guy - and on;y you will be able to work that out.
I guess that if he does ask you - or if things do go further, make it clear to him that you want it to stay between the two of you - and that if anything gets out - it won't be happening again.

Your friend is a slut who is only using you so he can have sex with you...think about this...if you 2 do have sex is he going to still hang out with you afterwards???