Years ago I went to a job interview where the woman interviewing me was very much not fannish. In her office as I approached, I saw a long-time fannish friend. Unfortunately, I'd only heard his real name mentioned once and knew him only as "Renfield."

Without thinking, I started to exclaim "Hi," and realized I couldn't call him "Renfield" at work and stopped.

Fortunately, he saw where this was going quickly and, without missing a beat, exclaimed, "Why Hi!"

(Yes, I got the job. :-) )