Halloween costumes is a great opportunity for colleges and other institutions to lecture people about avoiding anything that is offensive. My observation is that virtually any costume could be offensive to someone.
To demonstrate the concept of universal offensiveness, consider the old bed-sheet ghost costume:
Here are examples of why it is offensive:
Some people are scared of ghosts; they could be triggered.
Some people have cultural or religious beliefs about ghosts; the costume may be offensive to these them.
The ghost costume may remind someone of KKK robes; don’t even go there . . .
Game rules: Please post examples of costumes and logic of how they are “offensive”. Since offense is in the eye of the offended, there are no wrong answers.
For background, here are some links on PC costumes: