Doing something that will make a lot of memories. Hist stands for history, meaning those memories are historical to you. Often happens when going on an adventure, a night out or a journey. It will be full of your own history.
We are going on a histful adventure
1. Nutting in a pillow
2. Getting your or someone else's pubes stuck together with cum
1. Your pillows are really hot if like to fluffernutter in them
2. "dude when I pulled down my pants this morning, I realised I had fluffernutter in them"