On 9/20/14, Josh sent a message that simply read "Hey Michelle." There was no response for a long time, but in December, she said, "Hey sorry my phone died!" Then in January 2015, he wrote back "Sorry was in the shower."
After Josh replied in May 2015, Michelle wrote back again that December, saying she "had a really busy week." A full ten months later, Josh wrote back, saying he's busy with midterms. Then in February 2017, she wrote back to say "Presidents Day had me swamped recently."
Josh sent one more message on July 7, 2017. He said he's been slow to respond because he "just got over serious a serious relationship when he was a sophomore in high school." In other words, they've kept this joke going for nearly three years now.
Not only did people think it was hilarious, but some people thought it was a sign of something more. At least one Twitter user thought they should get married. But that might be pushing things just a little.