> something horrible based on timezones, or phone number validation What? Do you have something against zip codes and email addresses? I like to ask something

> something horrible based on timezones, or phone number validation What? Do you have something against zip codes and email addresses? I like to ask something to do with strings - English sentences. I tell them it's intractable in the time we have and that I really want to see how they whitebox-test the code they write, so take ~10m timebox to write the code, then write some tests - at least one test that finds a bug.