>the ':()' shows that we're making a new function named ':'. Everything inside the '{}' is the function body, it makes two recursive calls to the ':' function and puts them into the background with the '&' so that execution continues instead of waiting for them to exit. Then it ends that command with the ';' and executes the function ':'. That makes 2 calls to ':' which each make 2 calls, and so on until ulimit or your hardware capabilities stop it.
I'm honestly surprised at all the downvoting for this. It's quite literally a powerful command for linux, and let's be honest, you deserve what you get if you type random crap from the internet into your computer. People who have seen it get a chuckle, people who haven't enhance their erudition. Everyone wins. Perhaps adding a link explaining it would have been in order, but failing to do so doesn't, in my opinion, justify nuking the comment from space.
Not sure if this is referring to the almost-troll, or the downvoting of said almost-troll.
Without an explanation it's humor for people who know, malicious to those who don't, and at best undermines the trustworthiness of the average comment on this site, which is abnormally high for the internet.
