Season 2 - BOO! (Dan and Roseanne outdo each other while trick or treaters come through their haunted house)

Season 3 - Trick Or Treat (Roseanne's car breaks down and she goes in the Lobo lounge dressed as a lumberjack and pretending to be a guy)

Season 4 - Trick Me Up, Trick Me Down (Roseanne feels neighbor Kathy is out for revenge for a prank she pulled on her)

Season 5 - Halloween IV (A Christmas Carol Halloween style starring Roseanne Scrooge)

Season 6 - Halloween V - (Roseanne tries to get Dan to play a prank on Nancy meanwhile David is spending time with another girl while Darlene's away)

Season 7 - Skeleton In The Closet (Roseanne thinks Fred is gay after spending time at Leon's party)

Season 8 - Halloween: The Final Chapter (Roseanne And Jackie use a Quija board)

Season 9 - Satan, Darling (Rosemary's Baby final season fodder)

I'd have to go with "Boo" (the first one). I remember when that one first aired. It was great.

Some of the later ones were too weird. I'd like to see the "Christmas Carol" one again, though. That sounds cool. I forgot about it.

Skeleton In The Closet