**JS** `(f=function(){ console.log('hi!'); eval("("+f+")()") })()` Function fun! A function that creates another function with the same body as itself and then runs it. It will display hi at the end when the stack limit is reached and the entire thing collapses. Disclaimer: you'll not be able to do anything in your browser until stack limit is reached. --- <strike>And another one, more **evil**: `function f(){ var tab = window.open(); tab.f = f; tab.f()}()` It creates a function which opens up a window, then creates a function within that window which is copy of the function, and then runs it. Disclaimer: if you'll allow opening of popups the only way to finish this will be to restart your computer</strike>