The Option at Callahan's Place (and it's successors) is the explanation of the peculiar ritual about the price of drinks. A customer purchases a drink. They may opt to consume the drink and return the glass, after which they are entitled to take change from the cigar box at the end of the bar near the door. Alternatively they make take The Option and walk up to the chalk line, make a toast, and smash their glass in the fireplace.
After it is explained most newcomers exercise The Option as a lead-in to talk about whatever is on their mind. The Option is also used frequently by regulars to show agreement and support of a toast or to commend a particularly bad pun