1x14 - Ruby Gloom

The two Mr. White ghosts are fed up with Boo Boo pulling pranks on people instead of scaring them. So now they try to teach him the right ways of being a ghost. Meanwhile, Ruby tries to help Scaredy Bat overcome his fears and Skull Boy tries to act more civilized after burping rudely in front of Ruby. (From: http://rubygloom.wikia.com/)