You can already feel a weird sensation under that rubber tail, what must be your flesh reshaping to fill it out. Apparently, they weren't kidding when they said it's usually much quicker than 24 hours - that must be for a full costume or something, because this is happening way faster than that. Panic-stricken, you try once again to pull the tail off, yanking at it with all your might, all to no avail. Another thought hitting you, you run to your kitchen and grab the sharpest knife you've got, trying to cut into the glove. Not a chance - it just sort of gives as the knife touches it, leaving virtually no chance of actually cutting it. Not that this should be a surprise: the package did say that you couldn't take it off or destroy it. You try yelling at it yourself, screaming "HAND! HAND!" in the hopes that it'll just turn back to a glove, but you know from the start that it's not going to work. The glove won't react to you, it'll just change you.
By now, the tail that's quickly becoming a part of your anatomy must be around half-developed, and you can feel it inside of its latex cocoon, pulsating as it continues to grow. You have to stop it! But how? The only thing you can think of is to get someone else to make it move, but who could you try? You can't risk anyone you know figuring out about this, so... of course! Grabbing your telephone book, you flip to a random page and dial the first number you see.
Busy tone.
You dial another one.
Ringing. Ringing. Ringing.
"Hello?"
"Quick, say the word hand!" You scream it into the phone as desperately as you can.
"Do what?"
"Please, just say hand!" The desperation in your voice is palpable
"Who is this? Are you another one of those jerk kids?! Look, if this is some kind of joke, I'm not laughing!"
Realizing that the person on the other end of the line isn't going to say it unless you do some explaining, you slap your latex-covered hand to your forehead and... wait, latex-covered hand? But he didn't... You look back behind you, a furry brown dog tail wagging about. You look to your left hand, the glove back in place. Dejected, you don't even bother saying anything to the random person you called, hanging up the phone and sitting down (or trying to - it's a bit harder with a tail) so that you can try to get your thoughts straight.