Each year the IDL Expert Programmers Association inducts new members (by invitation only) into its membership. Each new member must answer the year's Test Question correctly before they can be inducted into the Association. Inductees have only one chance at a correct answer, unless the judges are still arguing about the correct answer (likely most years), in which case you may put forward two answers and ask the Presiding Officer to flip a coin for you.
Here is a small sample of Test Questions so you can get the flavor of what might be asked.
Question 1995: What's the difference between IDL and PV-Wave?
Answer: Uh, the name!?
Question 1996: Why in the world would anyone want to use a widget when they have the goddamn command line right in front of them? [Submitted by Chairman Coyote.]
Answer: Yes, yes. It's a commie, liberal plot to bring more female programmers into the ranks. It will not be tolerated.
Question 1997: Does the IDL PostScript driver suck or what!?
Answer: Yes, but according the the documentation that's the way PostScript is suppose to work.
Question 1998: How many contour intervals can you expect if you set the NLEVELS keyword on the CONTOUR command to 15?
Answer: No more than 12 or 13, depending upon the phase of the moon.
Question 1999: If you set the PostScript LANDSCAPE keyword to 1 and you wish a YOFFSET of 1.0 inch, how many reams of paper will the average IDL user go through before they realize they have rotated the graphic off the page?
Answer: No more than 12 or 13, depending upon the phase of the moon.
Question 2000: What is black and white and "red" all over? (Hint, it is not a newspaper.)
Answer: An IDL user with a new 24-bit graphics card.
Question 2001: Is is possible to make a filled contour plot with colors and contour intervals exactly they way you want them?
Answer: Not really.
Question 2002: What OpenGL graphics card is best to use with object graphics?
Answer: Any one that doesn't have "Windows" written on the box.
Question 2003: What undocumented function must you know about if you want to programmatically do anything whatsoever with iTools?
Answer: Well, if I told you it wouldn't be a secret now, would it?