My (40 at time) friend (38 at) and I had gotten tickets to see a band in our city. Come the day if the gig I gave him a ring to arrange meeting. He told me he was feeling rough but his fiance (38) would have his ticket as she was also a fan of the band. We met up and had a few pre-gig beers. Just chatting like normal. We went to the gig and in the crowd I was stood behind her kind of watching out as it was a pretty raucous band. Her arse bumped into me a few times. I knew she was engaged to my friend but she had a nice arse and I am just a man so I got hard. It seemed that once she noticed my hard cock she "accidentally" bumped it a few more times and kind of rubbed her ass on it a couple of times, which got it throbbing. I thought nothing if it at the time. After the gig I asked if she wanted to go home but she said she'd like to stay out for a few more. We went to a bar close by and got some cocktails. The talk started about the gig we'd just seen but quickly turned sexual. She was being very flirty and touchy. At one point she went to kiss me. " But you're engaged to ***** l" I said. "I want to fuck someone before I'm married. If it's not you it'll be someone else. I'd prefer you because I trust you" she said after a pause. She then walked off to the toilet. I thought about this while she was gone but as my cock was still hard not much of the thinking was done with my brain. "I've got a little present for you to help you make your mind up" she said on her return from the loo and handed me her knickers. I couldn't help myself and gave them a good long sniff. They smelled like heaven. "Have you got no knickers on now?" I (stupidly) asked. She just smiled at me. "I'll have to check this" I said and put my hand up her skirt. My fingers very lightly bruched her bare pussy and I felt she was wet. She moaned very softly. "Fancy finding somewhere quiet for a......joint?" I asked. "Yes, I'm gagging for a....joint" she answered while staring into my eyes. Fuck! We were doing this! My city has lots of canals so we went to a shady spot I knew near an old disused spur from a canal. I pulled out a joint and started smoking it. She stared at me for a moment before saying "fuck it" getting on her knees in front of me and getting my cock out. She looked at me for a second before puttin it in her mouth. If you've ever smoked a joint while getting your dick sucked you know how great it feels. "Holy fuuuuuuck" I said and reached my hand down her top to feel her small but perfect tits. She had one hand on the base of my cock while the other hand was up her skirt. She abruptly stood up and told me to fuck her before taking the joint out of my mouth and bending over a small wall. I got behind her, rubbed the head of my dick around her now sopping wet pussy. I positioned the head of it on her glistening opening. "You're sure about this?" I asked before pushing my cock in without waiting for an answer. "You dirty fucking bastard" she barked before saying "fuck me hard, I make love at home and it's been years since I've been fucked." This was all the encouragement I needed to grab a fistful of hair with one hand and her hip with the other. I started to fucking pound her! "You're a filthy fucking bitch. Taking your blokes mates cock down here by this dirty canal." I told her and slapped her arse hard enough to leave a red handprint that I hoped would fade soon. "Maybe when I've finished with you I'll leave you here bent over this wall for anyone else who wants to use you" I said. "I'm a fucking slut" she moaned as she started to quiver all over. "Fuck, fuck, fucking hell" she shouted as she came and pushed me off her. "Sorry, I don't think I've cum that quick before, it was too intense having you inside me" she said after she got her breath back. "Do you have another joint?" I did so I lit it and passed it to her. She had a few drags then passed it back. As I started to smoke it sat on the wall she got on her knees and stated sucking my dick again. At one point a homeless guy passed by on the other side of the canal but she didnt care. She wiggled her arse and put on a bit of a show for him. Eventually I could feel the build up. "I'm going to cum" I warned her (as a gentleman should). She sped up her sucking and I grabbed her head as I shot down her throat. It felt fucking amazing! We cleaned up a little and got our clothes back on fully. We hadn't kissed once during all of this. As we were walking back to where we could get a taxi she gave me a kiss on the cheek. "That was fun, it won't happen again and if you tell anyone I'll fucking kill you" she said. "I'm telling nobody about that and it might happen again" I told her but she was right. It didn't happen again.