xkcd.WTF!?

Explanation ➲

Michael Phelps is an American Olympic swimmer, who could easily be considered the best swimmer worldwide: he is the most decorated Olympic athlete of all time, with 28 medals, 23 of them gold (won in the 2004, 2008, 2012 and 2016 summer Olympics, so it would have been 18 Olympic gold medals at the time the comic was published). He was most dominant in the 2008 Beijing Olympics where he won gold in all of the eight events in which he competed, the record for a single games.

Cueball and Megan find that the Olympic medalist is in Megan's pool. He refuses to leave, and is too fast to be caught. Cueball brings in boxes of Jello Mix to fill the pool with, thereby gelifying the pool and trapping Phelps or forcing him to leave.

However, according to the title text, after having waited the time necessary for the water to gelify (roughly 2 to 4 hours), Cueball realizes that Phelps has eaten all of the resulting Jello. This adds yet another level of absurdity to the situation. This may be a reference to Phelps being used to eating impressive food quantities (about 10,000 calories daily), to keep up with his strenuous exercise regimen; or it may be a reference to pictures of Phelps smoking from a bong that arose after the 2008 Olympics in Beijing, as marijuana use is often associated with an increased appetite. Otherwise, the text may simply be a reference to Phelps being capable of achieving super-human feats, such as devouring an entire pool full of Jello. However, eating an entire pool filled with Jello is incredibly absurd even compared to these feats of consumption. Filling an entire pool with Jello would take approximately 5.5 million packets of Jello and would equate to about 440 million calories. If Phelps kept up with his 10,000 daily calorie diet and ate only Jello, it would take 44,000 days to finish the entire pool of Jello, or about 120 and a half years.

Interestingly enough, just pouring Jello powder into a pool would not solidify the water into Jello. The water would have to be boiled, then quickly chilled, for the Jello to set correctly. As Randall is a scientist, he should have known this; therefore, it's possible that he purposefully ignored this fact in favor of the humor. In 2019, YouTuber Mark Rober made a video where he showcased a pool of Jello that he had made and described the science behind it. Michael Phelps' top speed is also only around 2.3 m/s, which can easily be outrun by anyone on land.

The title text may be referenced by 1628: Magnus, where people are thrown into strange contests with others, for example a hot dog-eating contest against the championship race horse Secretariat.