Why? Well, because bears sleep through Christmas.

4 seconds sound clip from the The Bear Who Slept Through Christmas movie soundboard.

You can hear this line at 00:00:49.383 in the VHS version of the movie.

Quote context

[...]

- Ever since Christmas began, everyone has looked forward with wide-eyed wonder to its annual arrival.

- And everyone everywhere celebrates the yuletide season as a time of renewed hope, goodwill, and peace.

- Everyone, that is, except bears.

- Why? Well, because bears sleep through Christmas.

- In fact, from about the beginning of winter until about the beginning of spring, bears do nothing but...

- Did I say all bears? Well, that's not quite right, because there was a bear a Christmas or so ago whose curiosity was stronger than his instinct.

- His name was Theodore Edward Bear.

- Ted decided to stay awake and find out for himself what Christmas was all about. This is his story.

- Patty Bear?

[...]