By now, Evan's two-incher had grown to it's full length and was throbbing fit to burst. Evan could not wait any longer, and neither could Willie. Evan penetrated Willie's virgin bootyhole with gusto, and began pumping.
"Oh my gosh, Evan!" moaned Willie, "That feels so Algebraic!" Evan said nothing, and continued pounding. Being 12 years old, Willie did not have much of a wiener to speak of. Nonetheless, he began massaging the spot where a penis should be, crying out in pain and pure ecstasy while he did so. They did this for about 26 minutes, before Evan suddenly stopped.
"What's the matter, buddy?" Wilie questioned, "You run out of juice so soon?"
"Naw, man. I just had a great idea! You remember my stretchy powers? The ones that make me grow huge?"
"...Yeah?" Willie answered cautiously.
Suddenly, Evan's two-inch-long cock expanded in Finn's ass. It grew and it grew and it grew. Willie began screaming, but not because he was in pain, but because his body was now being filled with Evan's beautiful genitalia. Evan continued to grow until his doggy lipstick was 300 feet long and as wide as a city block.
"Evan... You really are a true bro." Willie squeaked out, barely able to speak.
"Thanks, dude." Evan said, and smiled. He knew that now, Willie and himself were inseparable friends. Nothing could ever come between them. And with that heartwarming moment, Evan continued. Evan kept pumping and grunting, back and forth, in and out of Finn's backside, his doggy balls slapping on what was left of Willie's body.
"B-Bro. I think I'm about to come!" Exclaimed Evan. "Let's come together, as one! As true BROS!"
And they did. Evan released his load all inside. Willie So forcefully, in fact, that some came spurting out of his mouth. Evan's jizz flew so far, it even reached Lumpy Space, hitting the Lumpy Space Princess in the face.
Evan shrank down to his original size, and exited Willie. Willie's body has been wrecked beyond recognition by Evan's large phallus, and he now resembled a large pancake made out of flesh, with a boston creme filling.
"We did it, Evan... We really did it." whispered Willie. He had not much time left in the world. Evan recognized this, and moved in closer.
"Yeah, buddy. We did." Choked Evan, fighting back tears as the realization that Willie was going to die swept over him.
Willie raised his hand, and made a fist. Evan did the same, and bumped it against Willie's. And with that final heartwarming moment, Willie passed on