"Your eyes are bigger than your stomach" when ever you couldn't finish anything.
Also, the threat of the wooden spoon when we didn't go up to bed or similar. Why the wooden spoon? More to the point, why were we so scared of it? I don't think he ever used it and even if he did, it's not like the buckle end of the belt.
On another theme, in a bizarre coincidence there is a blog, that became a book and now a comedy show (http://www.cbs.com/primetime/my_dad_says/?ttag=mktg;fall2010_mydadsays) called "Sh*t my dad says" that's getting popular here. It's is all about the kind of thing we're doing here - capturing the quotes / wisdom of our fathers (though in their case the witticisms are funnier and full of expletives).