The Reddit Hug of Death is an internet event best known at first as the Slashdot Effect or slashdotting. It's caused when a user from a much bigger websites makes a link to a smaller website crashing the sites servers due to the massive influx of traffic.
The Reddit Hug of Death is well known on Reddit and when a post specifically asks for links, such as when the default subreddit r/AskReddit with it's 11+ million subscribers poses a question like "What is your favorite website besides Reddit" That question will have dozens of comments along the lines of " ITT What site can Reddit Hug to death today"
Usually within minutes of a website being linked in a popular Reddit subreddit the site is indeed down, for hours and sometimes days depending on the popularity of the thread the link originated from. If a post's popularity causes it to reach The front page of Reddit seen by vast #'s of Redditors, all but the most robust sites will experience server problems and most experience the Reddit Hug of Death.
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