I'm not a mannequin, but I'm usually posed,
I'm very selective, like a lock that is closed,
until you can find it, the one thing that fits.
I'm liked by adults and loved by most kids.
I bring satisfaction, but only just once,
or maybe never, if you are a dunce.
If you don't get me now, you might get me later,
as in this special case, I like to be meta.

Panel 1:
G and H are walking.
G: You know, I’m not sure we’re going the right way. I think we’re lost.
H: Don’t worry. I think Birdcon is right behind this ... thing?
Panel 2:
In front of them is a Sphinx.
S: I’m blocking the way, but not like a fence.
For illogical reasons I give you a chance.
The riddles I pose may not be too hard,
for I only exist to make you feel smart.
What am I?
Panel 3:
G: Ahhhm, sounds like an identity crisis.
S: Correct. You may pass.