There are four known GIFs to the Khan Academy community. A GIF is an animated image.
The first is the loading sign. This is featured at the end of every math mission, and when most things are loading on Khan Academy.
The second is Jumping Hopper. This GIF is used in the CSS position tutorial in the HTML/CSS Making webpages course.
The third is Sully, this GIF is found in the Pixar in a Box section.
The final GIF is not as well known, as it is not used in many places on Khan Academy. This GIF is Mr. Pants sleeping.