Here's a simulator that creates suction to simulate the feeling of oral sex. Find some kind of short, rigid tube; the center of a roll of duct tape or packing tape works well. Carefully wrap a soft hand towel around the outside of one edge and through the inside of the tape roll, making it as thick as necessary to fit around your penis. Now unroll a condom, slide it through, and pull it into place through the opening; then carefully stretch it over the mouth of the tape roll. It's a big stretch and the condom could rip if you're not careful here. Secure it with a heavy-duty rubber band (like the kind they put around stalks of broccoli at the supermarket). Now lube up well and slide in your penis. This is the good part: To create suction, pull hard on the tip end of the condom as you pull out. It's a gentle suction, but it feels good as your penis pops out. Pull all the way out and let the condom fill up with air, and then push back in and feel the air burble out around your penis. This can get noisy, though, so you may want to do this when nobody is around.