Old man is asking for a pint of his alcoholic beverage however the bartender does not know what a pint is. This is important because it shows how the old man isn't used to the measuring system that's being used.
Winston asks the old man what all has changed since when he was young and he gives him information about something non-important. This shows there's not much he can do to compare the present day to the olden days because those who lived then don't remember the important bigger picture.
Winston finds a beautiful pink ball of coral and the sore worker agrees but remarks "but there's not many that'd say so nowadays" (Orwell 107). This shows that people don't value beautiful things nowadays because the party has robbed everyone of individual value and forced people to value the party and nothing else.