Billy was in shock when he found out that cold water could make him older. However, it was his mother, Lisa who can control his age and she had decided to make a little prank to him.
Billy's height shot up reaching his mother level and then towering her by a foot in a matter of seconds. He now looked like a very lanky boy but it didn't last too long. Muscles began to protrude from everywhere bulging his skinny arms and legs to well-built manly limbs.
However, thick calves and thighs are nothing without a proper pair of feet. They went from size 8 to 14 as his legs got beefy. Of course, his hand did the same to match the strong biceps of a brawny man.
"Mom!" Billy panicked in a deepening voice that was getting lower as his chest and back broadened with muscles. Now, he was definitely two times heavier than before.
Finally, all his skin was covered in a thick layer of hair. His legs, arms and chest grew curly brown hairs that could be mistaken by some ape fur. His armpits and crotch got a special treatment turning messier and bushier than before.
At that moment, Billy realized that he was naked and that his mother can see his junk. That wasn't the worst, because it was growing bigger and heavier as he grew older. His dick went from teenhood to manhood in his mother's sight.
Fortunately to him, that was the last change and he stopped growing at the age of 45, same age of his father.
"Wow! That was sick!" He said and he got surprised of how similar he sounded to his father. "I feel really weird!"
"You have grown a lot, honey!" Lisa said. "You aren't used to your body. Look for some clothes while I prepare some food."
"Ok, mom." He thought it was weird to say something like with the manly voice he now have. He walked to his bedroom, tripping constantly as he wasn't used to his bigger clumsy feet.
"Wow." Lisa said when she was finally alone. "He looks exactly like his father. Even his dick is as big as him" She was getting horny thinking on his son's package.
"Mom!!" Billy shouted. "None of my clothes fits me!!"
Lisa laughed a little before she replied.
"I'll go to buy you a few clothes after breakfast!"
"I won't... I don't want to go around naked..."
"Honey, you have nothing to be ashamed of. I have seen you naked since the day you born."
"It's not the same..." Billy sheepishly replied as he walked back to his mother. His bigger hands were unsuccessfully trying to hide a huge boner. "I feel so embarrassed right now!"