XDDD, very long story short one of Danny's recurring ghost enemies is a kid who can't be seen by adults (or people who think they;re adults) named Captain Youngblood. He likes to play ghost pirate. Complete with a flying ghost pirate ship, a skeleton crew, and a skeleton parrot.

...Their last encounter involved the kidnapping and brainwashing of every adult in town, midair battles between a blimp and the flying pirate ship, hand to hand fighting on the rigging, and lots of puns.