When you accidentally teach someone zero-based indexing while completely bombing a date. Look, most people think programmers can't get dates because we're socially awkward, but the real reason is we can't help ourselves from dropping computer science fundamentals into casual conversation. The date crashed and burned, but hey, at least she walked away understanding why array[0] is the first element. That's basically a public service. You've saved her from countless off-by-one errors in her future career she didn't know she was going to have. Silver lining: she won't be one of those people who thinks arrays start at 1 like some kind of mathematician. You took one for the team.