Harry, the 20 years old son of the family, called this best friend Philip in order to try the body swap machine.
I am this Philip and I'm 19 years old. I look like a geek because I'm one. I don't do sports and I'm not happy with physics. Today I'm at Harry house, my best friend. He is nervous because he just found that his father, a great misunderstood scientist, do experiments about body swap in his laboratory. Harry leads me to the lab. I see lots of electrical equipment, a big machine, with two cabins. Harry wants to turn it on and try it. We enter in each cabs and press few buttons. After a great flash I get out of the cabin and I am face to face with myself. Harry and I exchanged our bodies. That's incredible.
I examine my body. My hairs are now light brown, I'm a bit taller also more muscular. I wear Harry's glasses and clothes. He also touches himself then pulls his pants to slide his hand into his boxer briefs.
"Gee, it does not look very long" He winces.
I blush, I'm embarrassed that he discovered I have a small one.
"I will see yours" I replied.
Then I undid my pants and pull my boxers to look in it. Indeed, his dick looks bigger than mine, probably a normal size, 6 inches erect, and I envy him. Suddenly I'm hot. I need fresh air so I dress and go out of the laboratory. I came across Erin, Harry's sister. She is a classic 16 year old, small, light hair and quite cheerful.
On seeing me she said "Hey Harry what are you doing there?"
Incredible, she thought I'm his brother. Harry follows me.
Seeing him, Erin said "Oh hello Philip"
He replies "No, I'm Harry and he is Philip"
"What?" Erin grimaces.
Harry continues "Dad built a swap body machine." Erin is even more dubious. So he invites her in to show her.