Cath opened the drawer again and took out a box marked "Paula's Power Tool", which contained a realistic strap on cock, quite thick and about seven inches long, complete with balls! She wasted no time in strapping it onto herself, while I lay on the bed in anticipation of what was about to happen. I could feel Cath's fingers probing my arsehole, and realised that she was lubing me up with some KY jelly. She squirted the lube deep into me, and I turned round - the sight of my wife wearing this strap on was incredible. "On your knees!" she commanded. I felt the tip of the cock nudging at my anus. "Relax" she said, and the thick tip slid into my sphincter. The feeling was awesome. "Want some more?" she asked. "Yes please" I replied, and she very slowly started to slide the first few inches of the cock in and out of my hole. My own cock was as hard as rock by now - I couldn't believe how good this felt. Within a few minutes she was fucking me faster and faster, until eventually I was taking the whole length of the strap on up my hole. I could feel the balls slamming against my arse. "Now you get on me" said Cath, as she lay on her back. I sat facing her, and lowered myself onto her strap on cock. By now I was very relaxed and the cock went in easily, right up to the balls. I began to ride the cock, and at the same time she was bucking her hips, so that she could achieve maximum penetration. I couldn't hold out any longer; I felt the muscles in my anus tense up tightly around the cock as I approached my orgasm, and seconds later I was ejaculating another huge wad of spunk all over Cath's face and tits. I could see that she was coming too, one of the longest orgasms she had ever had with me. This was a completely new experience for me, and one which I can't wait to repeat tonight!