"Kuma" means "bear" in Japanese.
But bears (the animal) doesn't woof. The sound that they do make is growling and grunting.
So why do the bear community "woof" at other bears that they find attractive?
Thanks to Google magic, I'm able to find out why the word "woof" for sexual attractiveness.
It is said that during the 90's, the word "woof" is used to show sexual attractiveness by all, no matter what sexual attraction that the person has. It is a more subtle substitute for growling, like what some people do. So the word "woof" got into the Internet at that time so it starts to spread around. That's when the bear community starts to pick it up until now.
I am not sure how correct is this but at least it did shed some light.
Does anyone out there actually knows why do bears "woof" at each other?
P/S: There's actually #boxerday for bears on Twitter. Click here for more info!