Mayor Pete was swatting at flies during the CNN debate last night.
https://twitter.com/spook131/status/1156401179741413376
He smashed one on his forehead.

Then the smushed bug was on his face for most of the debate.
Gross.
Mediaite reported:
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Buttigieg was appearing on CNN’s New Day Wednesday morning where Alisyn Camerota asked him about the smudge, which confounded viewers of the Tuesday night debate.
“I have a totally cosmetic story for you?” Camerota asked “Did you have a smudge on your forehead and what was that?”
“So our best guess is that — there were these little gnats around. Maybe I smushed one and it got on my forehead. I don’t know. That’s the thing about having something on your forehead. Hopefully it didn’t distract from the message,” Buttigieg said.