Cock sucking fantasy

My interest in sucking a cock infront of my wife started a long time ago. My first real girlfriend and I talked about guys joining us, and I hinted that I'd like to use my mouth on the other guy but didn't have the courage to say I'd like to suck him.
One day I read a story in a porn mag about a guy getting a man ready for his wife. It said "she told me to make him ready for her, so I put my head in his lap and did as she instructed". Mmmm this was perhaps the start of my biggest fantasy.
Then another time I was watching an old porn video. When it came to the end a gay porn film came on - it had obviously been recorded over with the film I'd seen. It showed a white guy kneeling in front of a fit black guy with a very big, hard cock. The white guy began sucking the black cock. This was my first exposure to gay porn but it really made me hard. I started wanking myself as the white guy was turned round and the black guy slid his huge cock into him from behind.

The wife loves it when we talk about another guy joining us. Lately we've been talking about how I'd make him ready for her. She loves this idea, and always cums as I describe how I'd release his semi hard cock and take him in my mouth. She says she wants to wank another guy into my mouth. She wants to kiss and touch him while he plays with her big breasts and I'm made to kneel naked on the floor, sucking his big cock. She'd tell him to fuck her husband's mouth and fill it with cum. She loves the idea of him cumming in my mouth.

Update:
my sexy wife wanted cock last night. We were both on our sides facing each other. She reached for my cock and tried to rub it against her but it didn't really reach. "It's too small" she said. mmmmm I love it when she says that. "Yeah, we need to find a bigger one, don't we?" I said. "Yes" she said, "much bigger". mmmm I said "you'd make me have a good look at it, so I could see what a real cock looked like". "How would I do that?" she asked. I said "You'd put your hand on my head and push me down to his cock. You'd stroke his cock with one hand and push my head closer with the other. It would touch my lips and you'd tell me to suck it". Mmmm, she liked that and started groaning. I got between her legs and pushed my cock into her. I continued describing how I'd suck that big cock and how she'd wank him into my mouth. I described how the head of his cock would fill my mouth and she'd push my head down onto him. She got more and more into it and as she came I told her how he'd start to cum, filling my mouth. I said I'd love her to have a lover so I could suck his cock, make him hard for her. She admits she likes this idea. I love being able to talk about this with my wife and cannot wait for the chance to do it.