Do I know you? - what does it mean?

[Heidi]

Dear teachers,

I was taught that if you think you've seen someone before, but you're not sure, you can always ask this question - Don't I know you?

I was a little surprised to learn that. I was wondering if 'do I know you? can express the same idea? If it can't, what does 'do I know you? imply?

Thank you!

[Barb_D]

Tone of voice will influence this, but "Do I know you" would be used if someone behaved in a way that implied they knew you, but you did not recognize them. It suggest that person is being more intimate than is appropriate.

[Heidi]

Thank you, Barb_D.

If I think I've seen someone before, but I'm not sure, is it appropriate or polite to ask 'do I know you' in a nice and polite tone?

Thank you!

[5jj]

'Don't I know you?' is safer.

[BobK]

'Don't I know you?' is safer.

As Barb said 'Do I know you' can imply that the speaker disapproves of the objects intimacy. In fact, it can be an out and out insult.

b

[5jj]

As Barb said 'Do I know you' can imply that the speaker disapproves of the objects intimacy. In fact, it can be an out and out insult.

b

You can see the effect of a similar question, "who is is this person..?" here, from about 2.53 on: Longshanks - YouTube