Sounds like a sexy fantasy. Sadly I don’t have any advice for you if that’s what you’re looking for. Have you guys talked about sex stuff or kinks or anything like that before? The only way to know for sure if anything’s possible is to talk to hitm directly about it. You can think of some less direct ways to gauge his reaction or warm him up to talk about it, but if he hasn’t given you any other hints I’d say it’s a crap shoot. You’ll have to decide, knowing him however well, how you think he’d react and if it’s worth the risk he won’t take it well, or you could lose his friendship.
Otherwise keep enjoying the fantasy and wank away!
Thanks for the message!