What does this emoticon mean?

There are several emoticons that I do not know the meaning of. On another thread I learned that this one means Time Out, not 'I'm hitting my head with a hammer.'

What does this one mean?

I would think I am shutting down and I am out of here.

I always thought it was a Halloween one, but it might be for 'unmasking' or 'ghosting'/secrecy, or a zombie/horror thing?

turning into an alien?

Arrgghh!!! I've spent a fairly frustrating few minutes trying to hunt this one down. It appears to be a variation on the Alien skull (thanks!! ) and suggested use is when you think a poster is writing gibberish ('please decode?'). It's possible that the latest set of emoji don't actually carry this version more, hence the difficulty in tracking it down (had to finally go through Unicode.org)

I asked the same question on another thread. Still waiting for the answer. Hope it is useful because I like the color.

My favorite emoticon is back