Magic Tricks

I have had this for a week now. I've performed it for roughly 9 or 10 people.
At least 3 of them discovered the secret because the top wiggles a little if played with, and 1 said, "that's not a real coke cap. There's no printing on it"
It would be a perfect effect of there was a way to make the top part sit in more tightly and flush like a "scotch and soda" gimmick and if they printed the usual text on it like a real coke cap has. Other than, is a great idea and does fool most people. You'll just have to take your chances on who those people will be