This has been nagging at me, in the back of my head, since the "MineralMan Living Rent Free In the DUmmies Empty Heads" thread, in which someone posted this photo:

Being the kind of person I am, I just can't let it go when something nags at me like that. So I investigated, and came up with this photo - fair warning, graphic content:
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After finding that, I KNEW I was on the right track. So I dug and dug, and finally discovered what it was that was nagging at me. I've seen a face like this before, in my youth long ago. Thats why it had nagged at me, and why it took so long to come to me. I feel better now, after discovering the connection:

CMD