Reminds me of an interview I had a while ago. The interviewer in all seriousness asked me to code up a sorting algorithm on the whiteboard. He was more of a business person than technical so was probably thinking of insertion, selection and bubblesort.

I said sure, quicksort, mergesort or radixsort?

He just said "okay, let's skip to the next question". :)

I'd be tempted to ask under what circumstances they'd expect me to be coding a sorting routine... Seems a bit like asking an accountant to add two 10 digit numbers.