'Alison's new underwear

"Well, say a person were to use your device to become, well, your panties...." the headmaster began. "Would anybody be able to tell the difference?".

Just then it clicked in Walter's transformed head. "You want to become my... I mean Alison's new pair of panties!? But... why?".

"See, I could help convince the other teachers that this is all legit if they come up to you...".

"That is nice! But where do you want to get a pair of panties from to turn into?" Walter articulated the elephant in the room.
"Well, I grabbed some from the lost & found at school! You know, we could have a little cat walk with you showing them off!" the headmaster smirked.

Mere minutes later, Walter, still looking like Alison, was standing naked in front of the headmaster, holding a bunch of sexy panties in her hands.

"Damn, you have quite the collection here! Though I'm wondering, what are those white stains in these?" Walter showed the headmaster some dried up stains in one of em.

"Er...." the headmaster just snapped for air.

"Maybe I should try those white ones first? Before you become them..." Walter beamed at him.