What sort of situations might come up? If your an autogynapheliac, you might find yourself using it a bit too often. Take one possible scenario, guy transforms into a woman every weekend, one friday he does it out of habit, not realizing that him and his wife were going away for the weekend to a beachhouse. He transforms himself into a beautiful brunette, gets dressed, and admires himself.
"Honey NOOO!! why would you transform?! You know we're going away this weekend!"
His husband, realizing the mistake he's made, comes up with a solution.
"No problem babe, I transformed at 7pm, I'll just transform back in the morning"
"But honey, we're leaving at 5am to beat the rush, you knew that. Don't you listen to anything I say?!"
"Ok, still no problem.. I'll.. just.. pack like I'm going to be a guy, take the medallion with me, and I'll transform on the way"
Aaaand, inevitably, the husband forgot to pack the medallion, he left it sitting on the dresser, and about halfway to the beach resort, he realized he had.
"Oh crap! I forgot to pack the medallion! You gotta turn around!"
"No way, we're halfway there, it would take forever to turn around now, I guess your just going to have to deal with being a woman this weekend"
And he did.. his wife gave him a bikini to borrow, which he unfortunately had to wear. Oh sure, dressing up was one thing, but wearing a bikini was VERY revealing.
He couldn't believe the view he had now on the beach
Or let's imagine another scenario. The medallion works on the premise of transforming the guy into whosoever clothing they are. Now if he's smart, he'll keep his own clothes separated so he can always turn into a female version of himself. Or if he wants to be specific people, he can use those clothes. Now suppose he gets lazy, and leaves a shirt lying around, and a neighbor spills something on her blouse, and needs to borrow a shirt temporarily, so the wife grabs one nearby (that just happens to be his). And then he uses that shirt the next time he decides to transform, un-beknownst to him that he's going to turn into a copy of her.
"HA ha ha! oh honey, you look so adorable. You look just like our plus sized neighbor, how's it feel?"
"Pssht! I'm not even talking to you, the only way this could have happened is for her to have worn this sweater. I am locking my clothes up from now on!"