Booboo

Booboo is a ghost that appears in "Heat Signature." He helps Marceline prank Finn and Jake, but just as his fellow ghosts, he takes it too far. Likewise, he is portrayed as being cruel and mean. He seems to have had a spot in Marceline's gang that she was in back in the underworld.

Appearance
Booboo has the stereotypical body of an ghost, a pale, semi-transparent blue. However, Booboo has two heads each of which speaks.