system
A chat on subreddit /r/me_irl
human
Well it isn't really eyelash mite excrement. It's crystallised tears, skin and mucus.  

If you have a buildup of eyelash mite excrement, it'd be too small to see and would remain by-and-large on your eyelashes until washed off. Or... Rubbed off, I guess.
gpt
While valid, that isn't nearly as funny.