Well,I don't know anyone who says Christians
should masturbate!
Maybe your question is more on the order of, "Is it wrong for Christians to masturbate?"
Interestingly enough, the Bible says absolutely nothing about masturbation, so we are left to speculate and pontificate.
Gen. 38.9 is a passage and story that includes coitus interruptus, but that's not the same thing. The only other text that gets close to the subject of masturbation is Mt. 5.28 where Jesus talks about the dangers of lust. But I'll come back to that.
As far as the medical community is concerned, Katchadourian and Lunde say: "Currently no informed person should have any real concern about the deleterious effects of masturbation in a physical sense. Whatever concerns exist pertain to psychological and moral issues. Psychological judgments in this regard are based on the motivations behind the practice, the degree of dependency on this outlet, and the extent to which the practice excludes socio-sexual relationships."
Christian opinions span the whole gamut, since the Bible doesn't teach on it. Pastor Charlie Shedd (he and his wife wrote books about sex) says, "Masturbation is a gift of God." Dr. Jay Adams, Christian psychologist says exactly the opposite: "Masturbation is clearly wrong since it constitutes a perversion of the sexual act." Lewis Smedes takes more of a middle road: "The mood today is that masturbation is all right; only the guilt is bad. I do not want to dispute the modern attitude. ... The young person...needs to learn that the feeling of emptiness after masturbating is not guilt, but only incompleteness. In this way masturbation can be accepted, along with its frustrations, as a temporary plateau for his sexuality. It is not morally wrong, but neither is it personally sufficient." John White, pastor and teacher, says, "It is better to masturbate than to burn. I am glad that the younger generation has been relieved of a burden of guilt and fear that once haunted so many of us.... Masturbation is not a good thing, but neither is it a heinous sin." Dr. James Dobson weighs in with: "It is my opinion that masturbation is not much of an issue with God. It's a normal part of adolescence which involves no one else. It does not cause disease, it does not produce babies, and Jesus did not mention it in the Bible." Gary Collins and David Seamands claim, "It's high time we stop making such a 'big deal' out of masturbation and give it the well-deserved unimportance it merits."