Grandpa's birthday gift

Melinda and I were making our regular visit to her grandpa in the nursing home. this week was special though as it was his 85th birthday today. He had alzheimers and remembered little and never recognized us. Every visit he would call us by someone in his history's name. Sometimes it was funny as he oftn mistook Melinda for his deceased wife Betty or some old girlfriend. I would giggle when he would do this and grab Melinda's ass or boobs or make some lewd suggestion. Today was one of those days. He thought Melinda was Betty. When Melinda reminded him today was his birthday he smiled big and asked, "When do I get my usual birthday suck, Betty?" Melinda blushed and I stepped forward and said, "Now, seems like a great time, Bill." Melinda looked at me with shock. When she looked back her grandpa had his cock out of his pajamas and was stroking it. I was amazed that at his age his cock quickly rose to a full erection that was over 7 inches and thick. I could see Melinda was impressed too. Her grandpa looked at Melinda and said he was ready to who he thought was Betty. I walked over and locked the room as Bill looked up at y wife with hopeful eyes. I looked at Melinda with a smile and said, "Come on, Betty. It IS his birthday." I pushed up against Melinda's ass and whispered in her ear, "Come on, baby, you have sucked plenty of cock in your life. This is a nice birthday gift for your grandpa you love. Be Betty." Melinda slowly knelt in front of her grandpa. She looked back and forth between me and her grandpas stiff cock. Slowly her mouth opened and took the head of his cock in her mouth. Next she was bobbing her head up and down and even cupping his saggy balls. I was so excited, I knelt behind Melinda and jerked her pants and panties down and shoved my cock into her shockingly wet pussy. I began fucking her hard and she began sucking her grandpa's cock like a demon. He started shouting, "Fuck her, Johnny!" Johnny was Bill's b*****r, Melinda's great uncle. I would love to hear the story behind that memory. I watched the back of Melinda's head bounce on her grandpa's cock when suddenly he threw his head back and shoved her head down with both hands. As Melinda gagged I could tell he was cumming down her throat. I blasted my cum deep in her cunt at the same time. As Melinda pulled her head up. Grandpa looked her straight in the face and said, "That was great, Melinda. I always knew you would grow up to be a great cock sucker."