But sexual immorality and all impurity or covetousness must not even be named among you, as is proper among saints. Let there be no filthiness nor foolish talk nor crude joking, which are out of place, but instead let there be thanksgiving.

Ephesians 5:3-4 (English Standard Version)

Pastor John Stott on this passage:

But the reason why Christians should dislike and avoid vulgarity is not because we have a warped view of sex, and are either ashamed or afraid of it, but because we have a high and holy view of it as being in its right place God’s good gift, which we do not want to see cheapened. All God’s gifts, including sex, are subjects for thanksgiving, rather than for joking. To joke about them is bound to degrade them; to thank God for them is the way to preserve their worth as the blessings of a loving Creator.

quoted from God’s New Society: The Message of Ephesians (InterVarsity Press, 1979) page 193.