Animals popping up randomly

If you are not joking then this can be a mistake. May be there is some web script or a background process running.

So what you can do is:

1. Close browser and see if animal appears again.
2. If appears again then type ps -A in terminal and watch for any suspicious process and terminate it as soon as you see it.
3. If you can not see any suspicious process, restart your computer.
4. If nothing works feed it what it wants and pray to God that it runs away without harming you. :D

I found it... it was a Chrome extension (I think called "MMO")... I uninstalled it and the animals went back to their holes :)