Can we vary from mothers only?
My mother used to say "Haste makes waste", although what I heard the most was "Don't be smart young lady", to which I would defiantly reply "Fine! I'll be stupid!"
My Gram would say "Isn't he an odd duck...." about someone strange. She also would say "Yummy-Hum-Dummy!" every time she saw some sort of tasty dessert.
But my father had the best ones....
"Close only counts in horseshoes and hand grenades"
"Six one, half dozen of the other"
"I put a roof over your head and clothes on your back"
"It's a good thing his head is screwed on or he'd lose that too"
And then he had a variety of:
"He's one sandwich short of a picnic"
"His elevator doesn't go to the top floor"
"The lights are on but no one's home"
"He's not the sharpest tack in the box"
"He's one card short of a full deck"