A day for two friends where they spend the entire day together. They wake up early in the morning and are together until late late at night. They don't necessarily DO anything important, like go to the cider mill or go to the mall, but they thoroughly enjoy their time together.
Perhaps they lay on the couch and watch a movie in their pajamas. Perhaps they take a nap together. Perhaps they cook some pancakes, or talk about their troubles. Perhaps they cry, perhaps they laugh...
it's a Peanut Day, they can do whatever they want as long as they do it together!
"hey rachel, want to get up tomorrow and come over for a peanut day?"
"i don't know if we can do a PEANUT day... i have to run some errands with the madre."
"oh... well we could maybe have a mostly peanut day..."
"sounds good lovey."