Hank was finished with his morning workout having showered, walking back to his locker wrapped in a towel to grab his stuff. He pulled his clean clothes out of the cubby before a stale smell caught his nose, dragging his eyes back into the space. A white jock sat in the back, faded and covered with grime. It must have been there before he arrived.
He didn't know why he reached out grabbed it, lifting it out of the locker and holding it in front of him. His eyes trailed the straps and the stains, wondering how long it had been sitting there, who had owned it. He wasn't prepared for what happened next.
Without thinking he pulled it to his face, inhaling just like he'd do to check any of his old laundry. He panicked for a second, realizing what he'd done before its scent rolled across his mind like a fog, wiping away any thoughts. His eyes dimmed as a vacant smile took over his face, his brain relaxing as a light high took over. His body stood like that for a moment, letting the fumes settle into his head before his hands dropped to his side.
Muscle memory took over, pulling the underwear around his freshly washed junk before he finished getting dressed. He walked out of the gym, forgetting about the dirty elastic wrapping his waist, its filth slowly tainting his nethers.
He went around the rest of the day with its smell still heavy in his mind. As he sat in his office it became the only thing he could think about, not realizing the source was still attached to him and contaminating the air. He didn't realize its grunge had spread, curls of hair spreading out from the elastic as his own musk was replaced with the rank scent of the jock. He felt two pins in his nips as the wave of hair made it up to his chest, two piercings materializing on his nips weighing them down.
He had already started to sweat from his new layer of insulation, quickly filling the air with his musk. He completely lost all focus, his mind fading to the background as his scent filled his head. He was unable to realize the changes to his body, the fur filling out along his arms or the thick beard that wrapped his jaw. It only worked to trap his scent even more, each breath filled with the vapor from his body.
He blinked, realizing the day was over, and absentmindedly started heading back home. Except he wasn't headed home. Instead he pulled up to some seedy looking bar in a neighborhood he'd never been in, other men that matched his new appearance walking in. He followed, finding a wall of lockers with the original smell of his jock heavy in the room. The small part of him still alive in the back of his mind realized this must be where it was from as his body pulled off his clothes, revealing the filthy hirsute man he'd become. He walked into a doorway hidden in the darkness, spending the rest of the night there until he was as covered in fluids as the jockstrap showed.