there are lots but it depends on your turn on's

I like to do it in front of my male straight friends

Use cocoa butter or baby oil for lubrication, get it thickly saturated on you testicles and your penis, and around the area. Use both hands, massaging your testicles cupped in one hand and slow, sliding motions with your penis with the other. Keep your legs pulled in with your heels against the ceramic base if you are on a toilet. Fold your legs in a setting position if you are on a bed. Take a towel and roll it and take a plastic garbage bag and wrap it tight around it, or something soft with the same slick surface texture. Place this bundle on top of a pillow and lubricate the top of it and liberally in your crack between your hips. Straddle all of this and slide slowly forward and backwards on it while you massage your testicles with one hand and penis with the other, applying pressure on your anus. Focus on rubbing your cum on your belly and chest when your orgasm comes, and dream of someone standing and watching you the whole time. Take a pair of split side running shorts and remove the inside liner, and the threads that hold the side flaps together up to the waist. Make a point of letting the person that arouses you seeing you in these, with no underwear underneath. But make sure the wind isn't blowing at the time! Later when you are alone, remember when that person looked down at your shorts in surprise, and raise a flap and begin rubbing your penis exposed, pretending that they are seeing this too. Have everything prelubricated, testicles and penis, when you bring your hand down to expose it. You can also wear these some day that you are around this person, and set down with your drawn legs in their direction. Unknowingly have an open space available so that they can look up your shorts and see a small portion of your testicles. Have the middle seam well to one side of your package so that an open space will be available. Keep your head turned well away from them, being distracted on something else, to give them plenty of chances to glance up there. Later on, masturbate in this same position, remembering how they sheepishly looked up your shorts. Start by slowly and accidently pulling on them from above and to the side, exposing more. When you get the shorts pulled back to where you can see them yourself, delicately ease your fingers down there to touch them, pretending those fingers belong to that person. Continue on from there. Actually any loose shorts would work.

I enjoy shoving a dildo up my ass on the highest vibration(male G-spot) and then lubing up my scrotum and penis. I stroke the scrotum for 3-8 minutes while on my knees in a doggy-stlye position. Then I make the dildo go in and out with my left hand while masturbatig with my right hand. Its a great feeling and to be honest im a little horny talking about it. :D