Slip McScruff is most afraid of neutral ghosts.  You know where you stand with evil ghosts and good ghosts.  You avoid the evil ones and maybe call in for an exorcism.  You chill with the good ones and introduce your girlfriend to them.  Neutral ghosts leave you in unclear territory because you don't want to let your guard down, but don't want to be the asshole.  When Slip was a teenager, he went into a moderately haunted house on a dare and thought the weird occurrences were malevolent, so he got it exorcised.  The ghost only had a hobby of shifting dishes around because of their compulsion and was "survived" by a large family of other neutral ghosts.  Slip has never lived down this traumatic experience of tearing apart a ghost family for no good reason.

Luckily he doesn't encounter ghosts much in his hockey career because these arenas are all new and state of the art.  Only a couple are built on top of burial grounds, but they took all league standard spiritual cleansing precautions.  In a very on brand move, the New Orleans Specters actually have a ghost on their roster.  Slip isn't bothered by this however, because that particular spirit, Nicholas Williams @Nictox, is mostly harmless.