As the two of you lay on the bed you take a glance over at your two costumes that are currently hanging on the back of the bedroom door. At first, they look normal, but then you notice something wrong with Jack's wolf costume.
It's got a human head. Not only that... It's Jack's head!
"Jack, check this out!" You lean over and tap on your friend's shoulder. It's no use, he's way too distracted. Jack's spine has obviously changed to something more wolfish because, well, he's giving himself a blowjob. Not only that, but he's growing fur now. The changes are taking place much more quickly. Fur grows all over his body, and subsiquentally disapears from the wolf costume. Within a matter of second, Jack is a full wolf, just like his costume.
And just as the transformations finishes, the Jack costume vanishes. He's stuck as a wolf forever. Just to be clear, he's not a werewolf, but an actual wolf!
Now you're worried about your own changes. Will they fade away? What of the costume? Can you change back? Hundreds of questions run through your head, but then you notice that the wolf has stop pleasuring himself, and is glaring at you with a massive hard on.