Someone who remembers how you take your tea has paid attention without being assigned.

Nobody was asked to learn it, which is exactly what makes it count. The information was picked up during a moment that was about something else entirely, stored without being requested, and produced later without being announced. Attention given as part of a job is valuable; attention given when nothing required it is a different thing altogether. It says somebody was actually present while you were both in the room.

Learn one such detail about someone this week and use it without pointing at it. How they take it, which chair they prefer, the name of their brother. Do not mention that you remembered.