This is one of the less impressive interactions on this subreddit, though it gave me a giggle this morning.
I work in a section of a large open-plan office. Rather than being a simple oblong-shaped room we have an additional space built extending from one of the corners, and this is our little section, shared between two teams.
The first team that takes the bulk of the desk space is the external communications team for our organisation. The second team consisting of three data scientists is the team I work in. The two teams have little-to-nothing in common and are only occupying the same office space because the arbitrary office configuration made it thus. I'm in the unfortunate position (literally) of having my desk closest to the "entrance" to our part of the office. I'm also unlucky that the two desks next to mine that belong to my colleagues can be unoccupied for several days each week as they both job-share between two organisations. This isn't unusual in our line of work, but I work for only the one organisation and I'm typically at my desk everyday.
Most people know that there's two teams here, and for those that don't it's usually pretty easy to work it out - I have one monitor dedicated to colour-coded mathematical computer code and one monitor dedicated to the charts and tables I create with it. My back faces the "entrance" to the office, hence my large monitors are fully visible to those people behind me, including anyone coming to talk to me or the other team. If you're coming to visit the communications team then the stuff I'm working on should be a clue that I'm not your man. Occasionally that fact doesn't seem to register with some people who want me to be the administrative assistant of the other team.
Whilst deep in debugging-mode this morning with big headphones on playing white noise two people approached my desk. I wasn't expecting visitors so I assumed they were waiting to talk to one of the members of the other team who may have been on the phone at the time. A quick glance to the side tells me that they're staring at me and will have questions. I stop my debugging investigations and remove my headphones.
Visitor: Is Dave (communications team manager) in?
Me: Dave isn't at his desk and I've not seen him today.
I was going to be helpful and say "Perhaps you could ask one of his team members..." but the the visitor moves away before I could and he looks around at the sitting members of the communications team who're all on the phone. I take my chance to dive back into my mundane coding for the morning and replace my headphones. The visitor continues to look around before returning his gaze in my direction and tries to ask me another question, but he stops himself mid-sentence when he realises I've replaced my headphones.
Headphones come off again.
Visitor, annoyed: You're not part of the comms. team, are you?
Me, with Cheshire-cat-esque smug grin appearing all over my face: No.
Visibly annoyed with the situation, the visitor moves closer to the other members of the communications team and waits for them to finish their telephone calls before dealing with his request. I'm delighted - my purposely blunt demeanour may have annoyed him, but it was his fault for making assumptions in the first place.