Am I a Friend Or Are You

i am a thing that does what is told bud does not do what it is told when i do it i don't but do but what do i do do i do or do i not when you look for me i am here but i am not here when you look for me i am here but i am not am i here am i here or am i not am i a man or am i a woman only time will tell but i will tell you this i am your best friend love me or leave me but you will be my friend to the end