Q: What do you call a bear with no teeth?
A: A gummy bear!
Explanation: The soft, red part that your teeth seem to come out of is called your gums. When you lose a tooth your gums will probably bleed a little but it is nothing to worry about.
A gummy bear is a type of candy (also spelled gummi bear). I like how they feel when I bite into them.
A bear that has no teeth probably still has gums. This play on words makes him a gummy bear and makes this joke funny.
There is also a TV series called Gummi Bears. Here is the first episode: