"Are we going to use this as our excuse to do our drinking contest?" Or...well just general drinking since he doubts it would be much of a contest. Getting drunk right now sounds just overall pleasant.

He takes the rum and adds some of it to the drink. He's not entirely sure how much he is supposed to add and his knowledge of mixed drinks is non-existent but he figures it would probably be wise to start small and build up to it. So he adds a small portion to start. Could always add more next time.