I have a question. If someone wishes you happy birthday, do you reply? But I guess, for some people, it's just so hard to do. Call me fussy, mean or whatever, but I think it's corteous of you if you reply even a simple 'Thanks!' to the wisher. Or acknowledge that you have received the birthday greeting! It's just frustuating. The wisher takes the initiative to remember and wish you, so just reply. That is it! At least the wisher will know that (a)The birthday boy/girl has received the message and (b)they did not wish the birthday boy/girl on the wrong day or something. Even if the wisher got the birthday day mixed up, tell them. It won't hurt you. It's just being polite.