Or have you sometimes lost your sense of self? Apparently this happens when you're on LSD
But it could be induced just by thinking
Do you feel that the world is a just bunch of feelings, sounds, pictures all arising and passing away? And that there actually no 'I' or 'my' or 'self' but just an illusion of it? The feeling of 'me' of 'I' is just a neutral feeling that arises that we mistake to be the 'I' or the 'me'
So whenever 'you' see an object, there's no you but only the seeing
I think that drugs - certain drugs - can alter one's perceptions. This is not the same as 'losing one's ego' or 'I'. You are simply intoxicated in that state, and the experience of losing yourself is part of the experience of taking the drug.
In my point of view an "I" is a person with own skills and ideas which is separate from a group.
An "I" have so much confidence in his own that it is living for itself. Some of them are genius, some of them are (an eccentric) artist, but there is a feature which is connect to all kinds of I: They are an ego. And some of them are walking alone all the time...