We’ve all heard them before… “If you run with those scissors you’ll fall down and put out an eye” or “Finish those lima beans, think of all those starving children in Europe/Korea/Biafra/Ethiopia who’d be happy to have lima beans to eat”. They’re getting old and tired. We need new ones… contribute generously.
To get us started
If you ever do that to your brother/sister again I’m sending you away to Neverland to live with Michael Jackson!
I’ve obviously chosen the wrong venue… should have tried this one in the Pit I guess…
My favourite one is “what would grandma say?”…well it works and i like it.
bad parent mB
me, that is.
My mom always threatened making me go live with my biological dad. 
On the glass counter of a shop I used to visit in my childhood, there was a sign in beautiful hand-written copperplate:
“Children sitting on this counter will be flogged”
Because I’m your mother, that’s why!
Has always been used by my SO on her boys, and still works to this day! (‘kids’ are now 29/27 y.o.!)