Anecdote from the past

I remember this funny incident from the past when my brother and I were visiting my grandparents.

There was a phone call for grandpa and my brother was taking the call on his behalf. After taking the message, my brother promptly asked the guy on the phone "Who are you ?". After he had hung up, I called my brother aside and told him that it was considered crude to ask "Who are you". I told him that a better way would be to say "May I know who is calling". My brother took note of this (.. So I thought).

After sometime, there was another call for grandpa. It would have been a perfect deja vu, had my brother not ended the call asking "May I know .... (2 second pause .. since he had forgotten the rest of it) ... who are u" :)