I remember having that issue in the past. I always insisted that I wanted him to do whatever he wanted, but he insisted that I told him exactly what I wanted. What I ended up doing was talking dirty, but avoiding the use of "dirty words" like fuck, cock, pussy, cum, etc. I would say things like:
"My entrance is dripping with excitement."
"I want to glide my tongue over your shaft."
"Every inch of me is yours."
It sounded respectful and classy but also very sexual. It also helped me develop my submissive persona, who (obviously) ended up being the most elegant, feminine entity I've ever known.
I still used words like clit, nipples, breasts, and anything that didn't sound so vulgar. Then again, a lot of doms want their submissives to be vulgar. Try asking him which he prefers.