I first tried this out when Nat and I were playing with another couple we have known for years, in fact they were the first couple we ever "played" with. They are a lovely and very highly sexed couple and over many meetings with them both Natalie and I have become totally comfortable with them and started trying out lots of stuff we would never have thought of. As both Natalie and Tiffany (name changed), his partner, love multiple penetrations he and I got into some pretty close positions together. Once, about a year ago, he and Tiff were enjoying a 69 and I was shagging her at the same time (I think Nat was taking a "fag break") and I suddenly felt my balls being sucked and played with. I love this and after a short time exploded in Tiff's puss. Well after that the ice was broken a bit and he and I do go for a bit of oral on each other which the girls love to watch and help us with, sometimes criticising our technique!
I have had oral from a guy a few times since then, although when swinging I tend to keep the fact that I am cool with this a bit quiet in case it freaks the other guy of the couple out. Also I have to admit I don't mind sucking the odd cock if its a nice smooth one Natalie laughs at me for this, she says "whats a nice one? They are all nice!" but I know what I mean!). I also must put on record that guys do give very good bj's! Maybe its like the girls say about bi experiences - only a girl knows what a girl likes - could be similar
with guys.
Nat loves the fact that I am cool with this stuff, and in fact admits its a big turn on to watch me "playing the pink oboe" as she so delicately puts it. I find that in a close foursome situation with another couple its great if there are very few barriers and if
something presents itself in front of my face and looks like it could do with sucking or licking (male or female) then I tend to go for it.
You do tend to err on the side of caution with new couples though. We met and played with one couple a few times until we found out the other guy loved some oral "bi-play" and that was only because he noticed one of our ads somewhere we had put that I could be orally bi. Both of us had kept quiet about it in case it freaked out the other one!