New patients who ring for an appointment, then try to hang up (their cats must be on fire) after I mention an available timeslot without giving me their name (or other pertinent details). "Oh good, I'll see you then!" (Um, hang on a minute!) Plus, there is certain information I need to give you so you're appropriately informed/prepared for your initial consult, so take a minute or two (literally - it's not that long) to listen.
Really - where on earth does it work that you book a medical appointment and just turn up without giving your name? The very thing we need to actually MAKE a booking! Even more interesting - I ask their name (Saying something like "I can book you in at 3pm if that suits, so if I can just get your name and a few other details for the records"), get the details from them, then have them say "Oh, it's not for me - it's for my husband/child/resident green blob etc" Changes the situation if it's not for you! (The clue would be "I can book YOU in etc...")