"Things You Wouldn't Know If We Didn't Blog Intermittently."
11 October 2016
Via the Enough Trump Spam subreddit, where the image credit was attributed to Imgur user, FayeKalius. The image may be a composite; if the hand positions have been Photoshopped, I'll take the post down, but a Google Image search shows other similar photos.
Addendum: a tip of the blogging hat to reader The First for locating other images from the second debate to confirm that the arm positions are not Photoshopped. Example here.