Unsettled Tom is a "meme" based on the panel of Tom with a hangover from Chapter 9: fuds choice, Page 8. It was originally used as a reaction image, and gained popularity in March 2019, nearly seven years after the page was uploaded.
The panel originally came from chapter 9: fuds choice, Page 8 where Tom wakes up with a hangover. The panel itself would not see a spike in popularity until a Redditor known as inactive_meme posted it on the /r/dankmemes subreddit, gaining popularity (as stated by the Know Your Meme article).
The format used in memes typically follows a format of one line expressing an action or posing a question, with the following describing a person who is unsettled by said question or action. The website imgflip would also add "Unsettled Tom" to its' random meme generator option as well.
Tom's face has also been repurposed / redrawn in different variants of the meme, including one edit where he is being dicked from behind by Spike (T&J). The "Sberbank of Russia" would even use the meme to help advertise, redrawing Tom to avoid copyright issues.