Usually it's just some simple question that requires a single loop. We explicitly tell them they can use any language including one they want to make up as long as they are ok explaining how it works. When possible, I try to relate it to the conversation we've had up to that point.

I've had someone start off by writing "four" on the board when prompted to write a "for" loop and get stuck. I'm still not sure if he was truly inexperienced or just trolling. The resume looked solid to me and he spoke well about his experience. I had almost decided to just skip the coding question as a result.

It's basically "find the first string in an array of string that has the letter 'b'" difficulty of questions. Anyone who actually codes can whip something up in a minute and we can move on. But it's always surprising how many people spend half an hour on that and still don't get anything workable.