There was no way he could hide his new appendage; it was just way too big, and very gross at that!
Jack grabbed the condom box, looking for a solution. Among all the animal-themed condoms he finally found one with a human silhouette on the packaging. This sounded promising, he thought to himself. It seemed only logical that the box provided for a way to change back, or surely there would have been complaints about the product.
He attempted to slide the condom over his horse cock, but it proved troublesome now that it had become soft, in spite of how much thicker it was. The thing would just not hold in place! Jack panicked for a minute. This had to work, damnit! Perhaps he just needed to get hard again to secure it onto his dick.
He started stroking himself again to get his erection back. At first his cock wasn't very responsive, but after a couple more minutes of stimulation, Jack felt the blood flow into his black member again. Sweating nervously and panting, he held the condom around the tip of his swelling horse cock as best as he could.
He gave a few more firm strokes, trying to maintain his erection long enough for the thing to deliver its effect. A throb ran through his length and his penis head started flaring again, dangerously stretching the condom. The dull, warm sensation returned, a sign that the condom was affecting him; Jack immediately stopped jerking, but it was too late... A tear appeared in the condom and it burst into pieces, freeing his engorged flare at its maximum.
An uncomfortable tingle ran through his cock and Jack witnessed it shrinking in spasms in front of his eyes. His balls started reverting to their previous state as well. Unfortunately the changes slowed down very quickly, and his erection settled around a foot in length. His member 's skin was still mostly back, with the distinctive equine tip as well as a middle ring down the shaft.
With no further stimulation, the head unflared and his erection eventually subsided into a pink foreskin, hiding all his equine features. Jack ran through the box to find a second "human cock" condom to finish the job, but could not find any. It looked like he would be stuck in this state for now... Jack's penis still looked huge, but at least it could pass as human when soft. He just had to be careful.
Jack hid the condom boxes under his bed and cleaned the mess he had made in his room as much as he could. He went to the bathroom to throw his stained clothes into the laundry machine, then jumped into the shower, washing the stench away from his body. He could not leave any clue behind for his parents to find out.
The shower had made him feel better, and he was getting used to the new weight between his legs. Now that his cock looked superficially human the situation wasn't so frightening. He adjusted his impressive package as best as he could in his clean underwear, pleased with the sight of his bulge.