I thought it was because when the uke lays down, his cum flows down his crack therefore making it "wet" Cloudy
Cum is not lube. It dries too quickly and isn't really slick enough to do the job and it most definitely isn't safe. Spit also isn't lube and won't save you from painful anal.
HOW CAN HE GET WET WHEN THIS IS NOT EVEN OMEGAVERSE???? IS HE SECRETLY A GIRL