To begin, I would suggest any activity together that at least gets his shirt off...basketball, tennis, running, working out on your own exercise equipment, hanging out at the pool, grilling on a hot afternoon, etc. This might help him become more comfortable being at least partially naked around you. If you have the opportunity to go back to your place after any of these activities, you may wish to take a shower to cool off. I'd leave the bathroom door open while showering and attempt to have at least some conversation through the shower curtain so that he knows that you are comfortable being naked with him nearby, even if he can't see you. If this is working, you can always finish your shower, and open the shower curtain to get your towel, revealing yourself to him. Regardless, you can wrap a towel around your waist for some time after your shower. After the shower, I'd put on some boxers, but nothing else to lounge around the living room. Pour some of your favorite cocktails for each of you and enjoy each other's company. Depending on how things are going, you may want to position your legs to either reveal your cock or at least the outline of your cock during this conversation. If he has remained shirtless during this entire process, and if he also showered with the bathroom door opened, I'd say you're making pretty good progress so far...As the drinks continue to flow, you can creatively direct the conversation to porn...For example, if you see a hot woman on tv, you can comment that this woman reminds you of the sexy woman in a porn video that you were watching the other day. If that seems to catch his interest, offer to plug in the video to show him. Once you've made it this far, it's up to your creativity to determine how quickly he's naked. Start talking about what's going on in the porn video...have you ever had sex in that position?...ever been in a 3-way with 2 women?...ever been in a 3-way involving another man and a woman (both men focused on the woman, of course, if he's str8)?...ever fucked a woman in the ass?...ever seen a dick that big?...man, I wish my ass looked like his...etc. If the video or the conversation gets you hard, nonchalantly start rubbing your own leg or your cock through your boxers. See what his reaction is. If he notices but doesn't say anything or seem uncomfortable, take it a step farther and reach into your boxers to stroke yourself. At any point that your cocktails are empty, get up and go to the kitchen to pour refills. Do not make any effort to hide your erection. Let it tent in your boxers or wherever it ends up. Make sure that you walk in his line of sight going to and from the kitchen, giving him every opportunity to see your hard-on (maybe even covertly cause your dick to stick through the fly). Continue rubbing your chest, legs, and cock. Keep the conversation going the entire time, talking about the video or both of your sexual histories. At some point, comment on how big his dick looks through his shorts (or whatever he's wearing at this point)...flatter him with comments that you wished your cock was that big...Whenever you feel comfortable doing it, tell him how horny you the video is making you and that you've gotta jerk off. If he doesn't object, continue watching the video, pull out your dick, and start jerking off. If you're lucky, he'll join in and do the same.
Depending on how this entire progression has worked, you may want to keep up the effort of making him comfortable naked or partially naked around you for a little while before making the suggestion that he let you suck his dick. Keep inviting him over to your place to watch the game, have a few drinks, etc., but let him know that you like to be comfortable when you are at home, and comfortable to you means no shirt and boxers only. Let him know that you don't mind if he stays in what he wore to your house or if he wants to get similarly undressed. Since you've already watched 1 porn video at this point, you can always work the conversation back to sex and porn at some point. Tell him that you were watching another porn video and thought that one of the scenes was much "hotter" than anything in the video that he'd seen. Offer to show it to him, then see how things go from there. If he seems to be open to watching porn with you, rent/buy a bisexual video that has a scene in it where there are 2 guys and 1 girl in the scene, and the woman is making the guys service each other in order to have sex with her. You can always tell him that a friend of yours brought it over in order to show you how sexy the woman in that scene was. After watching it together, ask him what he'd have done if he was one of the guys in that scene...if you were in a 3-way and the woman insisted that you suck the other guy's dick before she'd fuck you, what would you do? This can easily start a conversation about what he might be willing to do, what he fantasizes about, etc., when the sexual situation involves another man. During this conversation, share your fantasies with him as well...I've always wondered what it would be like to give a man a blowjob...I've never understood why it's "hot" to watch 2 women together, but that str8 men think it's "gross" to see 2 men together...I wish I had a dick like that guy's...etc. You never know what you might discover or what he might be willing to do...
If you make an effort, you'll find out pretty quickly how open this guy is to having any kind of sexual experience with another man. The important thing is to give him plenty of opportunities to show or tell you what he's interested in or willing to do, and to make him comfortable by showing and telling him what your interests and fantasies are. As he becomes more and more comfortable with you, you may be surprised with what he's willing to do...
I am bisexual and was closeted for a while, but all of these suggestions have worked for me with people that I've assumed were str8. After others know that you're comfortable being naked or close to it, many of them are too. I've had str8 roommates with no problems walking around the house naked, and jerking off while watching porn together. I've had str8 friends that go to the nude beach with me. I discovered that another str8 friend of mine sleeps naked, as do I. When we went out of town to a MLB game together, we went to a str8 strip club together after the game, but we were sharing a double room together and we each slept naked in our own beds. Once getting undressed for bed, we each walked to the bathroom naked, and the following morning, we each stood naked at the vanity to shave. I've had some threesomes involving myself and another male friend and a woman (no male to male contact in these cases, but I did get to see my friend hard, horny, and fucking another woman.
The main thing I can say is be comfortable around people and be open with your feelings and fantasies. Strive to enjoy life, and don't be afraid of being turned down. Best of luck!! I've had a very fulfilled life so far, so I hope you'll have the opportunity to do the same...