I was on the other end of this...if you're good buddies it shouldn't be that big of a deal if he says yes or no IMO.
I was house sitting for a buddy and he lived close to some bars so my other buddy that likes to shoot pool came over and we went out to see what kind of trouble we could find. Both without gf's at the time....didn't have much luck but had fun and got shitty drunk.
Got home, drank more and were both super horny...started talking about bj's and how awesome they are...lol I just said fuck it and asked him if he'd be down to get sucked! He asked if I was serious and what the deal was...I told him I'm not into guys at all but a nice cock and load is fucking hot...blame porn for that! lol...he agreed.
Wasn't but a min later and he pulled out his dick and told me to go for it
He's asian, about 6 but thick and omg did he shoot a huge load! Still to this day he was one of the biggest shooters I've seen.
A complete hot time that didn't mess anything up between us or make it weird....sometimes it doesn't hurt to take the chance and ask.