Try this on his mother.

Matthew was absolutely astonished. This app somehow was able to change the properties of things around him, including his very own cock!

“…holy shit…” He quietly whispered to himself as he felt his enlarged penis.

“Marcus?! Did you just swear!?” His mother responded sternly.

“Uhhh, no, sorry I was just thinking out loud!” He said as he quickly pulled his hand from his pants.

She turned away pressed with finished up the dishes. As Matthew discovered, he could get specific about things he wanted to change. Being curious and devious at the same time he thought of something involving his mother. As she was facing away he could get a picture of her backside. After highlighting her butt he made it much larger.

In her leggings her ass cheeks swelled up. The fabric of her underwear and pants slid into her crack, as two large cheeks formed. It looked almost a bit silly, but Matthew was stunned. As she turned away from the sink her large ass was viewable at different angles.

Matthew then felt strange. His enlarged member was making a tent in his pants! This was his own mother, but the power to warp her body was a turn on for him. He wanted to see what else he could do, and decided to warp her chest as well. He snuck a photo of her into the app once more, and got to her tits. Just like her ass cheeks they swelled up rather quickly, and now were saggy double d-cup breasts under her top. While the weight threw her off for a second she quickly readjusted herself, not paying any mind at all at the upgrade he had given her.

While this was fun to watch, he still felt the strain in his underwear and pants, even with a bit of precum forming. Matthew bit his lips, next he decided to…