Jeff has to watch as his mom picks out a shirt and a matching pair of shorts from the dresser drawers, knowing what's coming; Several hours of darkness. However, his worries were proven wrong when she actually dressed him; Jeff was able to peek out the top of Luke's shorts. So here he was; Locked onto his baby brother, only able to move his head, while Luke's baby penis pressed against him. And worse, he had Five days of this.
It got even worse when Luke sat down; Not only could Jeff feel Luke's weight, now almost crushing him with his smaller body, but he could feel as if Luke's butt cheeks were spread by how his body is.
==== Time Skip; 10 minutes later ====
Jeff was watching Luke play with some toys he got recently, when he felt that Luke needed to pee. This had suddenly worried him, as he didn't know how this would work. As he was thinking about this, however, Luke answered his question right there... by peeing directly into him.
Jeff could feel both the stream of warm pee being shot out of Luke and his penis putting pressure against him while doing so. As Luke was peeing, Jeff was also feeling the pee soak into him; His skin had started absorbing it. Every single drop started soaking into his body, with a sensation he somewhat enjoyed accompanying it. However, he was still grossed out; His baby brother was peeing on him, and he couldn't do anything!