I really don't get it. Is that one of Yahoo's characters or something? Or did they just put it there because they thought nobody would question it? I'm really thinking the latter at this point.
When YA started, they did not have their current "smilie" logo yet. They used the photograph of a toy first, which was a singing and dancing hamster. That toy became known as KungFu or Ninja Hamster, this is how it looked in the good old days, only jacket and headband were white http://ecx.images-amazon.com/images/I/41Y7QS5E46L._AA280_.jpg
One of the first users created another mascot: "Frank the Frankfurter" and since there were so few users and everybody seemed to know each other, he and his fans used to add "Vote for Frank!" to each of their answers.
But eventually the Yamster won, although he was switched for a cartoon version of the original toy, because as a user pointed out, it might infringe on some copyright...