...and [VERB] I do!

1 This phrase, and its sister phrase ...and boy do I (ever) [VERB]!, are used as exclamations to emphasize the degree to which you engage in a particular activity or action. It's used to echo a verb mentioned in a previous statement. 

When I arrived in Japan, the first thing I wanted to do was eat sushi. And èat sushi it díd! I ordered a huge sushi boat all for myself and ate the whole thing.

In this context, this phrase has the nuance «and believe me — I did exactly that: I ate a lot of sushi!»  

This same nuance can be expressed with boy, and less commonly with man. Note that the intonation is somewhat different. More defiant and proud; more like an exclamation.

When I arrived in Japan, the first thing I wanted to do was eat sushi. And bòy did I eat súshi! I ordered a huge sushi boat all for myself and ate the whole thing.

Note that with boy, you can leave off the verb. For intance, in the above example, it's enough to say And boy did I (ever)! In this case, the primary stress is on {DO} or ever

My brother and I are like best friends. But to be honest, I don't know how he can stand me. When we were little, he lived in mortal fear of me pranking him... and prànk him I díd! Every chance I got. I still can't believe he made it to adulthood without having a nervous breakdown.

My brother and I are like best friends. But to be honest, I don't know how he can stand me. When we were little, he lived in mortal fear of me pranking him... and bòy did I ever pránk him! Every chance I got. I still can't believe he made it to adulthood without having a nervous breakdown.