Inspired by The Many Memes of Meta on meta.stackexchange.
Catchphrases and concepts that spread from person to person are known as memes, which, courtesy the Internet, can now explode across the Earth like a highly contagious virus (hence "going viral"). As with their real-life counterparts, some infectious diseases are global (pandemic), while others are endemic to specific regions.
Let's list the memes of EL&U here to have a museum of EL&U memes.
Note: One meme per answer please.