My "short" shopping list

I'm going shopping with my parents today and have on my shopping list just three items: rechargeable AAA batteries (for this confounded optical mouse which has drained three pairs of AAA batteries in two months), a battery replacement for my Swatch watch and a few new ID cases (to replace my current one which has cracked and gotten torn). If I had shown this short list to my sister, we would look at each other knowingly and laugh. How many times have we drawn up a short grocery list and ended buying much more after being lured by temporarily reduced prices of "necessary" items!