And how...

Well, I know I have used "and how" for emphasis, but I'm not really sure of its roots. Maybe who, what, where when, HOW... as if someone covered the four former bases and needed the fifth to finish it off?

Just a guess, but maybe it's the beginning of an expression of agreement.

"He really made an impression"
"And how he made it."

"This work is awful."
"And how stressful."

IMO, this expression is rather dated now though. I don't think you would hear it much from anyone under 50. Or am I wrong?

What about Don Hertzfeld's cartoon "Rejected," where you see an ad for "bean lard mulch" with a stick figure saying "I'm a consumer whore!" and the other stick figure says "And how!" That is more or less how I like to use this expression...

This actually comes from the German "und aus" - which means, lo and behold, "and how". It basically indicates agreement with a previous sentiment or statement.

Variations of the German expression mentioned above include "und ob" and the most directly translatable to "and how" in the form of "und wie"- both of these are used in German in the identical way that "and how" is used in English (as posted by oestphemieri). The variations in German exist because of regional usage differences.