a flipside to that might also be to work those phrases from days of yore into your kid's vocabulary. it can backfire though - my daughter runs around the house ALL DAY screaming "no dice!" (a la charles bronson) and "people!" (as in: where i told her soylent green comes from.)
where god left his pants might be the best in my arsenal, but my buddy's' father had a good one. his neighbor had a ton of kids in their family, plus several dozen cousins, aunts, uncles, etc. always hanging around the house. i guess being in such close proximity all the activity annoyed him, so he'd always say: "you can't swing a dead cat without hitting a smith (not their last name, but you get the idea.)"