A university recruiter reached out on LinkedIn. I sent a resume and scheduled a phone screening. To be fair, I hadn't prepared as well as I should have, so the difficulty I had was my own fault. However, the interviewer himself was very distracted (I could hear him speaking with someone else on his end, and he was very slow to respond when I had questions). He asked me questions about something on my resume, but he phrased it just like a clarificatory question, so I answered briefly. Then he laughed at me, because I didn't go on to explain further.

Traversing a binary search tree.