Jack was dedicated to the craft of writing and kept a journal with him at all times. That's one sticking out of his pocket.
In "Belief and Technique for Modern Prose," he said, "Scribbled secret notebooks, and wild typewritten pages, for yr own joy."
Your Kerouaction for this day is to get a journal and keep it with you at all times (along with a writing utensil!). You have many choices. A cheap spiral-bound like Jack has in his pocket is fine. Or you could spend some of your hard-earned dough on a leather Celtic-knot embossed journal like the one I took with me all over Ireland and use as my daily journal (left in picture below). It's from Oberon Design. I carry this one with me wherever I go. Another choice is a Moleskine, seen below on the right. I keep this one in a pocket of whatever coat I'm using for the current season, so it's always close by even if I neglect to carry my main journal. (By the way, it's pronouned mole'-skeen.)
Why spend a little more money on a journal (as I have done and many people do)? If you value your journal for its beauty (let alone its cost), it's more likely you'll keep it with you. Then it's handy for all those times the writing muse strikes.
Oh, don't forget to keep it at your bedside for those foggy just-woke-up thoughts. Sometimes those are the best - Jack wrote Book of Dreams that way!