Yesterday I saw two young boys goofing around in a grocery store parking lot, not paying attention to the traffic around them. Their dad said “parking lot”. That’s all he said. The boys quickly stopped messing around and paid attention to where they were.
One or two word reminders can be effective while saving you from accidentally launching into a mini-lecture (“How many times do I have to remind you to be careful in parking lots!? There are cars ...”).
Another mom told me that when her daughter forgot to put her dirty dishes in the dishwasher after dinner she would just say “plate” and walk away. She said using a one word reminder was effective and prevented her from ranting at her daughter.