As was walking away from the grocery store, I heard someone call out "Hey, friend!". After it was repeated, I turned around and saw the guy who was next to me in checkout line, a few meters away and indeed, calling out to me. I went up to him and he asked if I work with computers. After receiving my confirmation and a question about why he's asking, he answered: "Ah, just testing my deduction skills, thanks. That's it.". I congratulated him as he headed towards his car and turned my own way, pondering what might've given it away.
Was it due to the bag that I was carrying on my shoulder, large enough to fit a laptop, which indeed was inside? Was it because I happened to buy a USB-A to USB-Micro-B adapter cable? Was that the general appearance? Compared to his athletic build, tan and well-groomed facial hair with a friendly smile, I was lanky, my face covered with zits, blemishes and uneven patches of growth, with a dead stare and expression of someone who's used to staring at computer screen for eight or more hours straight daily. Was it because of how I wandered around the grocery store avoiding any interaction, or how I'd awkwardly answer with only nods and and head shakes to the cashier who seemed to be extra talkative today?