you could always have one of them dream about having sex? and it could be all intense and hot and ooh we're so nawty and then Brendon wakes up (in my mind Brendon is the one having the wet dream ofc) and is all like, "fuuuck." i'm sure you could tie that in to demonstrate repressed sexuality or whatever as well if you wanted to.

(Ryan's SUPER SEKRIT JOURNAL OF SEKRITTY ARTISTY TINGZ is totally just full of porn. Everyone thinks he keeps it private because it's his art and his art is his life and he's all enigmatic about it because it's so important to him, but actually. Whole thing's just page after page of filth. :D )