Talking dirty?

Denise
My DH always asks me to talk dirty to him or tell him what I want during sex. For me it is distracting, I am NOT a talker during sex, I cannot formulate a coherent thought. If he say "tell me to......" I basically can repeat what he just said. Other than that I get very self conscious even trying to talk dirty to him....a anyway, has anyone else had this problem and overcame it? If so, how? I would love to be able to shock him with something I know he likes.