"I can't keep calling you honey if you're older than me." Lisa said. "What if I call you daddy instead?"
"D-daddy?!" Billy frowned in utter confusion. "B-but mom..."
"Please, call me Lisa."
"L-lisa... no, I can't!" Billy said as he shocked his head. "Mom, this is just temporary, I'm your son! Remember?"
"I know, but we are also two adults alone in a room." She replied in a seductive way while he rubbed her son's hairy chest. "I'm sure you are curious of what you can do with that body, aren't you?"
"I guess so..." Billy began to rub her mother's neck. "No! This is wrong! I'm sorry mom but I won't do this!"
Lisa was disappointed but she understood that her son was right. However, it wasn't fun just to make him older if they can't get some pleasure from it.
"Ok, then take a towel and wrapped around your waist." Lisa said. "And about your erection... well, I think of just one way to cool it down..."
Billy blushed when he understood what his mother was saying. He clumsy walked to the bathroom, tripping a few times with his bigger feet. When he entered, he closed the door and stared at himself in the mirror above the sink.
"Oh shit! I look a lot like dad." Billy said while he watched his reflection. "That's why mom was so horny back there... I can blame it, dad's hot and I think I look hot too, hehe." Then he stared at his dick whose tip was visible in the mirror. "Oh god, how embarrassing! Why I'm too horny? It's dad too horny too? Maybe that's why he and mom broke..."
Meanwhile in the kitchen, Lisa was smiling of how well her plan has worked. This was going to be an interesting vacation!