The riddle
What Do You Call a Bear with No Ears?
Spell it out
This riddle is about spelling, not about the animal. Write bear, b-e-a-r, and remove the three letters e, a and r that make the word ear. What is left is the single letter b. The answer is written "B" with a capital, and said aloud it sounds like the word bee.
The same cut on other words
Many English words end in ear, and taking it away leaves one letter each: pear leaves p, hear leaves h, fear leaves f, year leaves y, gear leaves g. Each of those could hide a riddle of its own. A group can hunt for more, which builds a feel for how often the ending turns up.
The letter B
B is the second letter of the Latin alphabet, and its English name is bee, according to Wikipedia. The article traces it back through Greek beta to the Phoenician letter bēt, the Phoenician word for house, which in turn goes back to an Egyptian hieroglyph meaning house.
Saying the letter
Wikipedia says b stands for the voiced bilabial stop in English, a sound made by closing both lips and releasing them with the voice on. The same sound opens bear, so the first letter of the animal is also the whole answer.
Where bear comes from
Wiktionary traces bear to Old English bera and, behind that, to Proto-Germanic *berô. Today's spelling hides the word ear inside bear, which the riddle asks the listener to spot; the older forms bere and bera did not. Try next: what is full of holes but still holds water.