A cheap fountain pen like a Lamy safari. Maybe some brightly coloured ink too.

Growing up I loved pens and my dad had some vintage Watermans he used all the time which were unquestionably Cool Pens but also really "fancy" so I wasn't allowed to touch them, and we just didn't know that way cheaper and less fiddly fountain pens existed because all of his came from the op shop with ink from borders and not an actual pen store. 8 year old me would've been estatic that not only do easier to use cheaper options exist, they're bright yellow and also you can put any colour in them, not just boring black.

...I feel like everyone answering "Powerball numbers" or "apple stocks" is completely missing the spirit of the question