One of my biggest pet peeves is any time someone tells you (the notional Internet user) to run something akin to the following:
curl http://somesite | sh
Few things drive me more bonkers than developers insisting on some form of the following. Worse, sometimes the program won't work at all without this format.
As with everything on the net there is now a Tumblr - curl|sh
I'm not sure whether to be overjoyed that this practice will get the mocking it deserves or saddened that there is an entire Tumblr dedicated to this practice.
(h/t: Matt McKeon)