There was this guy in my MFA program, and he did this thing that some writers do that I hate hate hate.
Here it is: you’d be talking to the guy, thinking you’re having a normal conversation, and then you or someone nearby would say something he found interesting, and he'd respond, “Oh, I’ve got to write that down before I forget it.” Then out would come the little notebook, and he'd actually do it. He'd write down what he'd heard with the utmost self-satisfaction at having captured ... whatever.
Like the world was his zoology experiment, and we were all just rare macaques for him to observe and report upon. Totally annoying.
I’ve been advised a number of times to always carry a small notebook so I can jot things down in case inspiration strikes. I don’t do it.