The one cookie belonged to both my sister and me, so we would express this as:
Maggie and Jenny’s cookie
(When both parties possess the same item, we only add ’s to the possessor closest to the item.)
Since my mom entrusted me with the sacred duty of splitting the cookie, I broke the cookie in half and placed the cookie halves back-to-back to carefully measure them. Then, I gave my little sister the smaller portion.
Since my little sis and I now possessed our own individual cookie portions, we would express that as:
Maggie’s and Jenny’s cookie portions
My mom apparently witnessed the entire transaction and punished me for my selfishness by taking away my piece of cookie.
Before you judge me and applaud my mother, you have to understand the dietary environment in which I was raised. You see, my mom was an aerobics instructor and fitness guru. Richard Simmons actually held me when I was an infant so my mom could procure greens from the salad bar in his restaurant. I was raised on Grape Nuts and Shredded Wheat (not the frosted kind). I was allowed only one piece of Halloween candy. Imagine: the most important decision of my childhood was whether my one piece of candy for the year would be a Reese’s Peanut Butter Cup or a mini Snickers bar. So, excuse me, if I wanted the big half of the cookie.
Did I mention it was a frickin’ OATMEAL cookie?
See for yourself. Here's a link to my mom's nutrition blog.