We have seen an owl animated login form and an envelope animated email unsubscribe form in the past. This particular login form animation in SVG was designed by Darin Senneff. When you enter the email the yeti becomes happier and when you go to enter the password it covers its eyes.
If you are having trouble with the pen, try the archived copy on GitHub
Mascot Animation on Login Form Snippet
See the Pen Animated SVG Avatar by Darin (@dsenneff) on CodePen.0