My Straight friend gets a boner around me everytime!

hey, I'm a discreet bi guy, i act straight but joke around being bi and stuff. I have this one friend who's kinda the only one who make me feel things sexual. I get a boner every time we are close and stuff, he gets a boner whenever I kinda touch him and joke or flirt. I tease to keep touching his junk, or just getting closer and making my body touch, he gets irritated or just pretend to be idk, I'm confused, I'm a fine looking guy too. Our other friends joke about us being a pair. And we both are virgins, we only kissed our girls once. Please help me out, it would made my life if I get into relationship with him (discreet obviously) but should I tell him I'm bi and I like him and he turns me on (don't wanna lose him as a friend). Please help me make him just go for me, he gets a boner with my touch, but I don't know he's actually straight or just shy or just disgusted or embarrassed or idk. We meet regularly and spent the evenings and the nights together (alone + with squad too sometimes) he's my best friend. I call him babe (he doesn't mind) i play around with his nips too (he let me do that) i hug him while we're watching movies or scrolling our phones (he doesn't mind that either)