Kyle and I had to return for another visit at the clinic where Dr. Topinbottom wanted to run some more tests. The two of us met up in the waiting room of the clinic where one of the nurses took us back to an exam room. When Dr. Topinbottom came in he said that he has been comparing both Kyle and I with one another and we're both very similar when it came to body type, ejaculation, and sperm count. The tests that he wanted to run that day was that one of us would have his prostate stimulated and the other would not. Dr. Topinbottom said that he was going to have me act like his assistant, and the first thing that he was going to want me to do was help undress Kyle to give him fellatio. Kyle dropped his shorts to the floor and hopped back up on the table looking at me. The Doc chimed in about the underwear needing to come off. That was when the instructions started to come in about what I needed to do. Dr. Topinbottom told me to grab the cock at the base of his penis very firmly. Then take the whole thing in my mouth. As I did so, I paused for a moment to make sure that what I was doing was right. The Doc told me to keep going, and so with the whole thing in my mouth I was working on trying to get him hard. I was told to lick his balls for a while, and as he started to get harder. The Doc made us pause to take off our shirts, so that we didn't get too hot.. When I went back to giving him head Kyle seemed to get a lot harder. Still the Doc wanted to show me some more techniques to use, by showing me himself. Pushing Kyle back against the table, Topinbottom took a hold of the throbbing cock and put it in his mouth. In watching the doctor he did this twisting motion with his head, as he went up and down. I stripped out of my clothes, and down to my underwear. I stepped in closer to Kyle; and I started to lick his nipple to have something to do. That was when the Doc tapped me on the head and told me to lick Kyle's ass hole. Kyle lifted his legs high into the air and while he was laying back, the Doc took off his shirt and dropped his pants. He exposed his raging cock that he had concealed before, and at least to me it was a turn on to see. On thing was for sure, Kyle loved getting his ass licked, and he was ready for probing. Dr. Topinbottom put on a condom and applied some lube to his dick and the hole. Going really slow, the Doc worked his cock all the way in the tight hole. Once he started to move in and out Kyle had a pretty constant moaning noise he was doing. Reaching for my cock and ass, Kyle wanted something to play with while he got fucked. I stepped in closer and jerked off really hard. I felt like at any moment my cock was going to shoot sending cum everywhere. I held back and let Kyle know that I was going to shoot, when I came most of it went on his chest and shoulder. As I was relaxed and got my breathe back, the Doc was still wanted to fuck Kyle. Wanting to try another position the Doc had Kyle get down on the floor and bend over the table. Putting his cock right back in the tight hole, they continued on with the fucking. From the sounds of things both of them were enjoying every moment of it. I think that Dr. Topinbottom was able to get in a lot deeper in this position, because Kyle seemed to push him back or tell him to slow down. However, they didn't keep that position for long, I think that the Doc wasn't far off from shooting his load. Kyle stroked his cock fast, and the Doc wanted to see a sample right away from Kyle. He started to order Kyle around, and when he came in a line up his chest in mostly one shot. That's when I was told to lick it up. I tried to get most of it up with my tongue, and I had to lick my lips a couple of times. Dr. Topinbottom wanted to get off, so standing in the middle of us, Kyle and I were on our knees in front of him. Sure enough when he came he wanted to give us facials. He grabbed the top of my head, pulling me in. He shot his load on my face and shoulder, of which some of it ended up in my mouth. The Doc told us to get cleaned up and to make an appointment for next week.