My friends and I always joked about our roommate being the Dad of the group. He was always the one double-checking plans and worrying about everything, keeping track of everyone. We'd even started joke calling him dad, something he didn't appreciate. We decided to take it to the next level, ordering some pair 'Dad Briefs' we gave to him as a joke. We didn't expect anything to come of it, surprising us when we saw him the next morning wearing them.
He had walked out for breakfast only in the whites, almost as if he was oblivious that he had nothing else on. We couldn't stop from snickering when we watched him walk out. His demeanor was had changed. He seemed absentminded, barely giving us the raise of an eyebrow before he returned to his room. We thought it was a funny one time instance, at least, until that was the only thing he ever wore inside anymore.
It was humorous at first, but even his mannerisms had started to change. He acted like he could do whatever he liked in the place, wear as little as he wanted since he was one of the names on the lease. He started drinking straight from the cartons, blowing us off when we argued with him. What made it uncanny was when his body began to change. Hair had started wrapping around him, and he began putting on a little weight in mass and muscle. Despite his receding hairline, his face managed to fill in with a beard, and he'd leave its trimmings in the sink for us to find.
We weren't sure if we called him Dad ironically anymore, but the name stuck. He preferred spending almost all day on the couch in front of the tv, just chugging beer rather than going out. We weren't sure what caused him to end up this way, but he seemed happy just the way he was. Just a growing hairy man in his dad-bod.