I think Richie would absolutely attempt to dye his armpit hair at some point and Eddie is both disgusted and intrigued. "God that's so gross Richie, next time make it pink"
(I HC that Eddie is generally a little grossed out by body hair cause his mom filled his head with the whole "underarm hair is unhygienic" nonsense growing up)
omg for sure, like i do imagine Eddie keeps himself very trimmed, makes sure he doesn’t have too much chest/armpit hair (and bc he has fair hair he never really has to worry about it anyway)
but there’s also the compulsory heterosexuality, where he’s meant to like the idea of clean shaven women, not burly, hairy men. on top of his mother pushing the idea of body hair being gross
so like, he’ll have a crisis when he sees Richie, thick dark chest/leg/pubic/armpit hair, and be so attracted to him - which only makes him panic more
like maybe for a joke he dyes his pits green for St Paddy’s, and Eddie would pull a face like “ew richie wtf” but also YES TO WHAT YOU SAID, he scoffs and is like “at least dye it pink or something prettier next time