Welcome to JavaScript where
Number.isInteger(0.9999999999999999) is false and
Number.isInteger(0.99999999999999999) is true

Not an office prank, but when I was in high school we had some public computers and I switched some shortcuts for chrome and internet explorer, so when you clicked chrome, something that should not be called a browser would open.
And than I got the brilliant idea: I wrote a script camuflagged as a chrome icon that would launch 100 internet explorers. Legend says that people are still raging to this day.

When they say 'Write comments!' and you are like:
// Do necessary operations

I have been refractoring a project with a SHITTONE of comments like this and a FUCKLOAD of nested if statements. And then this commes along:
$user2 = User.find($user->id);
WHO WRITES THIS STUFF? I am never working on a cheap project from India again.