This is something new to me and so I'm sharing with others because we all do it as a joke and out of normality/seriousness.
If someone is seeking permission and is asked who he is, he should introduce himself with his known name or his nickname. It is not enough to say: "It's me!" Imams Bukhari and Muslim reported that Jabir رضي الله عنه came to the Prophet 
and knocked on his door. The Prophet replied, "Who is it?", Jabir رضي الله عنه replied, "It's me!". The Prophet hated that and said, "It's me, It's me", meaning that he hated this useless response.
Source (to be verified)
REPLYING TO ‘WHO IS IT?’
When knocking on the door you may be asked: 'Who is it?' Identify yourself, using your most common name but do not respond with: ‘It's me’, or ‘somebody’, or ’Guess who?’ 'These words are useless in identifying who is at the door. The Prophet Peace and blessings be upon him discouraged one from saying: ‘It’s me’ because it does not reveal your name. Al-Bukhari reported that Jabir ibn Abdullah said: ‘I came to the Prophet Peace and blessings be upon him and knocked on his door and he asked: ‘Who is it?’ I answered: ‘It is me’ and the Prophet Peace and blessings be upon him disapprovingly said: ‘It is me, it is me.’ For this reason, the companions used to mention their names whenever they were asked: ‘Who is it?’
Source Darul Uloom Bury