Anything *is* possible, depending on the context.
  Can I fly crosslegged while touching my fingers? Sure - I can
  levitate.

  I could levitate in my mind.
  I could construct a picture *showing* me levitating and
  therefore, I levitated.
  I could get wires that lift me up to levitate.

  It only becomes a problem when "if and only if" is attached to
  the possible answers.

  Just the other day, I made a Vine telling people they could be
  anything. This girl wrote back, "Yeah, well I can't be a Unicorn
  for the rest of my life!"

  I said, "Sure you can. If you believe you're a Unicorn, you're a
  Unicorn. The people around you might not agree with you but
  that's their problem isn't it?"

  So, I'm saying the same thing as the above Meme, just in a more
  positive fashion. Since I believe that Delusion is _also_ the
  state of mind of the "Credible Proposition" person who made that
  graphic, I prefer to keep it positive. Otherwise people get
  cocky and actually believe they know something.