[UPDATE 2/18/2019, 3:37pm PT: Here's a statement from a Google spokesperson: “While we continue to investigate the matter, we have not found any evidence that Google Images was ranking the Pakistani flag in response to this particular search. Many news outlets wrote about an old screenshot from a meme website that is inconsistent with our UI and dates back to 2017, and we have not seen any independent verification that these results ever appeared as depicted. Since these news stories published, images from those articles are now ranking for this query, as the pages contain words relevant to the search.”]
[UPDATE 2/18/2019 I've learned that tt's likely the screenshot images are fakes, and are based on a 2017 meme. I'll post an update as I get more information.]
Unknown persons gamed Google's algorithm so that search results for "best toilet paper" returned photos of the Pakistan flag.
From BBC:
The results are believed to be the work of protesters acting in response to an attack in Indian-administered Kashmir that left at least 40 soldiers dead.
…
Now a Google search returns news stories about the link but anyone searching images for the "best toilet paper in the world" gets a page dominated by the green and white flag. Many of the images are from news stories about the connection. Others are screenshots of the critical social media posts that linked the flag to toilet paper.