What you usually call an abnormally very small penis. Normally the 'sir' is added to increase the penis's already low self esteem due to it being quite small.
Me: "Hey, Dude, how is Sir John doing? Did he enjoy last night with me?"
Dude: *Thinks: She called him Sir, so I really was mistaken when I thought it was small* "Sir John is doing GREAT, thanks."