Quote Originally Posted by welshdevondragon

I was just wondering if the phrase "he looks like butter wouldn't melt in his mouth" is something that Americans say. I want a 19 year old New Yorker at uni in Britain in 1999 to say it. Whilst I've asked a few American friends about this they've all been living in Britain for a few years now and are unsure whether they knew what this phrase meant prior to coming here or not.

Basically would it sound odd/ jarring to have an american say "he looks like butter wouldn't melt in his mouth"?

Any help would be great! Thanks, Alex
That's a pretty old expression. (According to my friend Google, it dates back to at least 1530.) It's not unknown in the U.S., but I don't think I've ever heard anyone actually use it in conversation, and I think it would sound awfully old-fashioned. So a teenager from New York? Not likely, unless s/he is the sort who likes to use idioms like that (and sound a bit archaic/pretentious).