Letter / Not a Letter

What's that

That is a letter

What is that

That's not a letter

That's a letter

That's not a letter

That is a letter

Is that a letter

I don't know what that is

That's so a letter

What is that

Whatever that is it's not a letter

That's a letter

Is that a letter or what

That's a letter

Only it's upside down

Letter / Not a Letter - They Might Be Giants