Obtain from giant notebook in dream bedroom.
Get from pink flower in flower world.
Get from an NPC holding a skateboard in the 2nd part of flower world.
Get from flame NPC in flame world straight down and slight right.
Wear a black coat and black shoes. Talk to Reaper NPC in flame world.
Talk to the well in ghost world and wait for countdown then talk to the blue NPC that pops out.
Talk to sleeping NPC in room world (purple door with a "Z" on it).
Talk to cloud bug in cloud world.
Get from talking to random head in heart world (after cloud world).
Talk to thing in the middle of the last room in white world.
Talk to girl on wall NPC in room 108 in white world.
Talk to skull dress in police station.
Talk to panda in bamboo world.
Solve riddle from girl under tree in bamboo world.