Don’t mind if I do

The subject being omitted is I: I DON'T MIND IF I DO.

In my experience, I DON'T MIND IF I DO is as frequent as the abridged DON'T MIND IF I DO, where YOU DON'T MIND IF I DO is never heard.

Suppose I'm invited to a party where the host comes around to me with a box of fancy chocolates. She says, "Here, take as many as you want." And I say, "Don't mind if I do." In this scenario, it does not make much sense to state that I do not mind if I have chocolates. (Why should I mind?) What would make more sense is to ask: "Are you sure you don't mind if I took a lot of them?" So, I feel that what is implied in the expression is actually a question of whether the person who is offering something minds my action or not. Or, it could be a request, as in: "Please don't feel bothered if I took a lot of chocolates."

"Don't mind if I do," is considered a polite way of saying yes when someone offers something to you, but I personally find it rude if the implication is in fact, "I don't mind if I do." "I don't mind..." means that I would not be bothered by it. So, if someone asks me to do something I might not want to do, the polite way to say yes is to say, "I don't mind..." For instance, at a party, the host asks me, "We need to get more beer, but I can't leave. Would you mind running out to get a six pack?" To that, I might reply, "I don't mind if I do." But when someone is trying to do something nice to me, why would I imply that I might potentially be bothered by it? It's like playing hard-to-get. Instead of saying, "I would love it," I'm saying, "I would not be bothered by it." It is rude to imply that someone might actually be bothered by the offering of chocolates.

"I" would make sense if the intention is to be sarcastic or tongue-in-cheek, but in that sense, it's not polite either. In other words, it is equivalent to saying, "These chocolates look disgusting. I'll help you get rid of them." However, in most situations where this expression is used, sarcasm seems inappropriate. This is why I feel that "You don't mind if I do?" or "Please don't mind if I do." seems more appropriate.

In any case, I wonder where the expression originated.

Also:

If what is being omitted is indeed the "I", then why was it ever dropped? Can you think of other expressions where the "I" is omitted? The omission makes sense if the statement is a request, as in: "Don't mind me."

It just occurred to me: If “Don’t mind if I do,” is actually a request (as in “Please don’t mind if I take a lot of chocolates.”), then the subject is not being omitted in that sentence. It is a complete sentence. This means that, even if we hear a lot of people say, “I don’t mind if I do,” and never hear anyone say, “You don’t mind if I do,” it does not prove that the “I” is being omitted or implied. It is possible that those who say, “I don’t mind...” are misusing the expression.

If the expression is supposed to be polite, then I could imagine it originating in England where a host offers a cup of tea, and the guest replies, “Please don’t mind if I do indeed want a cup of tea.” In other words, it’s a different way of saying, “If it’s not too much trouble, yes, I would indeed love a cup of tea.”

I think it's a jocular kind of thing, particularly omitting the I (which I do believe is omitted)--if the host is prone to over-analysis and is very, very easily offended I could see how he or she might think it rude for someone to say he doesn't mind accepting the offered kindness, but hopefully I never meet such a person. Although, as I'm from the northeast, I'm not particularly inclined to use that phrase anyway.

http://www.bbc.co.uk/liverpool/localhistory/journey/stars/tommy_handley/catchphrases.shtml

This is an interesting page I found. According to it, the phrase "I don't mind if I do" was popularized in the 40s through this radio program. Unfortunately, this does not clear up this issue since the addition of the "I" could have been part of this joke. If "Please don't mind if I do" was how the expression was known before this radio show, adding the "I" would make it funny. It would have turned a polite expression into a rude/selfish one, which this character apparently was.

My theory is that "Please don't mind if I do" was the original expression, and this radio show made adding of the "I" popular. Now, many people do not realize that the addition was actually a joke, and use it even in situations where they should not be joking.

"Don't mind if I do." is omitting the "I", but it the reason people say it is jocular is because it is ironic. "It will not be a great deal of effort to comply with your offer." It means, "I believe I will." but in an more enthusiastic way.
It adds emphasis to how burden-free the suggestion sounds to the listener.
"Please feel free to get the phone numbers of our lingere models."; "Please grab as many left-over slices of tri-tip as you wish."; "Would you like to use the restroom after your long trip, before we drive to the restaurant?"
In print, it is hard to understand, but when you see it being used it makes more sense.

Ok, you're in a restaurant. During dessert, your server comes to the table and says: "Would you like some more coffee?" You think for a moment, then reply: "I wouldn't mind that at all, why thank you." Now I ask you, does that exchange sound at all awkward to any of you? I think not. "Don't mind if I do" is just an informal way of saying the same thing.

When someone offers something, expressing that you wouldn't (or don't) mind isn't rude at all. If anything, it's a natural consequence of our upbringing. We're taught from an early age to downplay our desires, not "I want" or "can I", but "may I please". It's just a socially acceptable way of expressing a desire in a more roundabout way. Of course, there's nothing wrong with just "yes, please", but "don't mind if I do" with an elided "I" is an even less direct, and, therefore, perhaps more gentile way of asking for more.

Spiffy is most correct. I am an English speaker, and I use this expression quite often. It is an ironic idiom most similar to, "twist my arm". As in "Q: Would you like this money, I found it on the ground? A: Well if you must twist my arm." Or "B: I don't mind if I do."

It is ironic that you must be corrected to accept such a thing, and is said tongue in cheek.

The "I" is most definitely the subject being omitted, but the expression is not literal or impolite.