Jackfrost is a comedy-horror with a set-up very much like Child's Play (1988). On Christmas Eve, Jack, a convicted serial killer is being transported for execution. On the way the van collides with a chemical tanker carrying a chemical that bonds with the snow and Jack's DNA--and turning him into a homicidal snowman that wreaks havoc on the town.
Basket Case (1982)
Basket Case could have easily made my weird list as well. I remember watching this at 10 or 11 and having no idea what was going on, but I've grown to appeciate the humor and absurdity of the movie. It tells the story of a young man who carries his hideously deformed Siamese-twin brother around in a basket. The twin is deadset on getting his bloody revenge on those who separated them.
The Horror Show (1989)
This B-horror stars Lance Henrikson as a detective responsible for sending ruthless serial killer Max Jenke to death row. After moving into a new home with his family he begins to experience sinister visions of Jenke-- and becomes convinced that he has come back for revenge.