Jake's baby blanket is Jake's most beloved keepsake. It appears in the episode "What Was Missing," in which the Door Lord steals it. With the help of Finn, Princess Bubblegum, and Marceline, Jake gets it back and affectionately calls it "blankie." He keeps it hidden under the floorboards of the Tree Fort.
It is blue and has stains, which give it an aged look. It is large enough to barely cover Jake when he is normal sized.