A pointless phrase that is most often used on the internet.
It is used to whore for attention, because if someone is asking whether or not he or she is the only one, he or she should already know that the answer is "no," yet proceeds to ask anyway. Thus, "am I the only one" disguises a statement of opinion as a question.
It is also used to convince oneself that one's opinion is a unique, nonconformist take on things and everyone else are sheep (or worse yet, sheeple
Idiot: Am I the only one who doesn't care about Iron Man 2?
Dude: No, idiot. Everyone else who doesn't care about Iron Man 2 doesn't waste their time looking for discussions on Iron Man 2.
A common phrase with the connotation "I feel I'm in the minority on this subject" that has received ridiculous amounts of trendy hate from the socially-impaired unable to understand anything in a non-literal manner.
Honest Question: "Am I the only one who...?"
Person 1: "You're never the only one!"
Person 2: "You're never the only one idiot!"
Person 3: "Idiot, you're NEVER the only one"
Person 4: "Yeah, you can never possibly be the only one!"
Person 5: "We are so LOGICAL!"