My first bi BDSM experience was so long ago it started with an AOL personal ad :). I arranged to meet a couple who wanted a slave, a long drive away - I lived in Cumbria at the time and they were on Merseyside. As instructed, I shaved my cock and balls and bought some panties and hold ups, and arrived at their house - the door was open and the master met me in the hall and took me into the front room. He told me to undress and put on my lingerie, then put a leather collar on my neck and explained that when I was collared I was their slave. He left and a few minutes later mistress came in, in long boots, fishnets and carrying a riding crop, which she used to hold up my cock and inspect for shaving and cleanliness. Then she sat in an armchair and told me to get to work. I knelt down and began licking up her thighs and then teased around her clit, and sucking on her outer labia. She told me to get on with it so I settled down to a steady licking, and, after a few minutes, making plenty of noise with her juices and my saliva - they talk about eating pussy but there's always a lot of drinking. I kept up a steady rhythm for 15 minutes or so until master came back and although mistress hadn't come she was well on the way. She turned over so she was on all fours on the chair and master told me to kiss her arse cheeks - at the time it didn't even occur to me to rim her but kissing her cheeks turned me on so much - nowadays I'd have my tongue so far up her arse it would come out of her mouth. Master was stroking his cock and told me to suck it - my first time, I'd only ever wanked guys before. I just put the head in my mouth but he told me to take it deeper and soon he was hard and ready to fuck mistress while I watched. After a while he told me to put on a condom and I fucked her too - I felt a bit uncomfortable, that a slave shouldn't be fucking a mistress from behind, but came very quickly. He finished off coming inside her - again, these days I be in in a minute to lick his cum out of her, but it didn't occur to me at the time. I left on good terms but didn't see them again as it was a long way away - a big regret, because our first time went pretty well and genuine dom bi couples don't come along every week!