Flint is showing the squirrel the video game Psychonauts. Josh suggested the reference when I couldn’t think of any video games that featured squirrels besides the adult-rated Conker’s Bad Fur Day.
I like titles with double-meanings. This has a double-meaning as well as being a pop culture reference. Jen is telling Morty he’s expelled, so he’s “burned,” and Flint is literally burning squirrels in a video game. On top of those, Burn Notice was the title of a tv series I was watching during the time I made this page.