stepmuff
Your stepmother. Title usually given to a stepmother who is not popular with the stepchildren. Pairs nicely with the derogatory term for stepfather- stepballs.
"You're buying someone a birthday present from 7-eleven?"
"Yeah, it's for my stepmuff."
"Wow, I didn't know you cared that much for her."
"Yeah, it's for my stepmuff."
"Wow, I didn't know you cared that much for her."