15 minutes into the Brooklyn Nine-Nine episode "Cheddar" (s3, e18), Charles is lying on a coffee table, which then collapses. It's obvious he has a rectangular box or book in the seat of his sweatpants. No one mentions it. Was there a deleted scene that explained the rectangle in his sweatpants?
In the previous episodes, all the girls who dated Charles always commented that he had a perfect, bubbly ass. So in this scenario, the ass can't be an explanation.
When you see behind the scenes of Brooklyn 99, you find out that it's actually a sponge protection for Charles, since he was falling a lot in this episode.