When performing usability tests, one of the standard tasks we give people is to install a game, and the game we usually use is The Puzzle Collection. (Yes, it's an old game, but continually updating the game makes it less valid to compare results from one year to the next.)
One of the things that the game's Setup does that always confuses people is that it asks you where you want to install it and suggests a directory. If you accept the default, a warning box appears that reads, "The directory C:\Program Files\Microsoft Puzzle Collection does not exist. Do you wish to create it?"
People see this dialog box and panic.
Because it's an unexpected dialog, and unexpected dialogs create confusion and frustration. From a programming perspective, this is a stupid dialog, because of course the directory doesn't exist. You're installing a new program! From a usability point of view, this is a stupid dialog, because it makes users second-guess themselves. "Gosh, did I do something wrong? The computer is asking me if I'm sure. It only does that when I'm about to do something really stupid." They then click "No" (it's always safest to say No), which returns them to the dialog asking them to specify an installation directory, and they'll poke around trying to find a directory that won't generate an "error message". I've seen users install the Puzzle Collection into their Windows directory because that was the first directory they could think of that didn't generate the "error message".
Anyway, after the program is installed (one way or another), we tell them to relax and play a game. We say it as if we're giving them a reward for a job well done, but it's actually still part of the test. We want to see how easily users can find whatever it is they just installed.
One thing you can count on is that when faced with the collection of games available, for some reason, they always pick Rat Poker.
Each of us has our own pet theory why people always pick Rat Poker. Personally, I think it's that the Rat Poker icon is the most friendly-looking of the bunch. Many of them are abstract, or they depict scary creatures, but awww look at that cute rat with the big nose. He looks so cheerful!
Click. Another vote for Rat Poker.