What does “…, won't you?” exactly mean?

Question

Drop me a line and say hello, won’t you?

What is the meaning of the last part - won't you?

• Is this a way to say "do it!" the way a parent would tell their children?
• Or is it just another way to say please" without any second thoughts?
• Or something else?

EDIT to add some context: I found this expression on Brian Gordon's contact page. He is the author of Fowl Language, a comics book/strip which deals with the wonderful experiences of parenting the hard way. This is why I somehow expect the meaning to be the first one in my list, along the lines of the world of the duck parents of his books.

Answer 1

My experience is that its meaning lies somewhere between your first two reasonable alternatives. The emotional scale goes from hoping you will do it, to asking courteously (please), to expecting, to instructing, to demanding (Do it!). “Won’t you?” sits somewhere along this scale, probably near expecting. Other opinions will be interesting to read.