How to get the kids to gargle after they brush their teeth

One of the difficult things I have to teach the kids to do is how to gargle. Most of the time they bite their toothbrush, then they swallow the gargle water. So one day, I told them.. "Since you like to spit out your food so much, please spit out the water the way you spit out your food." and so they did just that.

But then they had difficulty cupping their hands and filling it with water to gargle and the adult cups are too big for them. So one day, I gave them their toy cups and told them to use those to gargle. They loved it! Now will somebody please help me stop them from gargling? Lol!

Now, my girl is such a pro at gargling, she can even throw back her head and do it. Sometimes they hold their little toy cups and say, "Yaaaaam Seng" then gargle. *rolls eyes*