You shouldn't drink martinis in the morning.
Don has had a rough morning so far dealing with stressful problems at work.
Don wants to take the edge off.
Don waits for his lunch break and orders a martini with his lunch.
Don prepares a martini and drinks it during his morning break.
Don's coworker enjoys a beer while he has the martini, and they have a relaxing lunch break.
Don's coworker notices him drinking early and thinks he is irresponsible.