( ・-・) I don't keep many drinks in my house, and when I had friends over once I bought some cans of Diet Coke for them.
( ・-・) They liked it, and have come to expect cans of Diet Coke whenever they visit my house.
( ・-・) In order to save money, washing up, and explaining, I instead buy large bottles of Diet Coke in bulk, then pour them into existing cans, before offering them to my friends "pre-opened".

( ・-・) I feel terrible.