Sonic, Tails, and Knuckles were lounging around, when Sonic had a peculiar idea. "What if we inflate our butts to surprise our friends?" he suggested, grinning.

Tails raised an eyebrow, considering the idea. "That could be fun, but how are we going to do that?" he questioned, looking at Sonic.

Sonic shrugged, glancing at Knuckles. "Maybe Knuckles knows? He's always coming up with crazy ideas," he proposed.

Knuckles, caught off guard, blushed slightly. "Well... I might have an idea," he admitted, scratching the back of his head.

Hours later, they found themselves at a peculiar lab with a strange machine. It was Knuckles' "Inflato-matic", a device he invented for fun.

Knuckles gave them a quick rundown on how the machine works. "It's simple. You just step inside, and the machine does the rest," he explained.

Sonic volunteered to go first. He stepped into the machine, and with a loud whir, it started working. Moments later, Sonic stepped out with an inflated butt.

Tails and Knuckles burst into laughter. Sonic, trying to keep his balance, joined in. His inflated butt made him look hilarious.

Next was Tails. He hesitated, but eventually stepped into the machine. The process was repeated, and Tails came out with his butt inflated.

Sonic and Knuckles couldn't contain their laughter. Tails blushed, struggling to fly with his new size.

Last was Knuckles. He stepped into his machine, and soon, he too sported a large, inflated butt. The trio giggled uncontrollably, ready to surprise their friends.

They decided to visit Amy first. As they approached her, their inflated butts wobbling, Amy's eyes widened in surprise and she burst into laughter.

Next, they went to see Cream. She gasped at the sight and then giggled uncontrollably. The trio was having a blast seeing their friends' reactions.

But as they were about to visit their next friend, the trio suddenly felt heavy. They looked back and saw their butts were getting bigger!

"Knuckles, what's happening?" Sonic cried out, struggling to run. "I don't know!" Knuckles replied, equally worried.

They hurried back to Knuckles' lab. But their inflated butts made it hard to move fast. They were attracting attention, and not the kind they wanted.

Once at the lab, Knuckles quickly examined the machine. "It seems the inflation setting was stuck on 'continuous'," he discovered, his face turning pale.

"Can you fix it?" Tails asked, his voice trembling. "I'll try," Knuckles replied, rushing to adjust the machine.

After a tense moment, Knuckles managed to recalibrate the machine. He sighed in relief. "This should reverse the inflation," he assured.

One by one, they stepped back into the machine. As predicted, their butts started to shrink back to their normal sizes.

Finally, they were back to normal. They sighed in relief, looking at each other. The adventure had been wilder than they had anticipated.

"Maybe next time we should stick to pranks that don't involve inflating ourselves," Sonic suggested, laughing. Knuckles and Tails nodded in agreement.

The trio promised to keep their adventures less risky in the future. After all, the most important thing was having fun together, inflated butts or not.

They all shared a hearty laugh, reminiscing about the day's events. It was an adventure they would never forget, a story to tell their friends for years to come.

In the end, the trio learned a valuable lesson about friendship and the importance of laughter. Even if the situation got out of hand, they could always rely on each other.