Ephesians 4:29
29 Let no unwholesome word proceed from your mouth, but only such a word as is good for edification according to the need of the moment, so that it will give grace to those who hear.
Colossians 4:6
6 Let your speech always be with grace, as though seasoned with salt, so that you will know how you should respond to each person.
James 3:2-6
2 For we all stumble in many ways. If anyone does not stumble in what he says, he is a perfect man, able to bridle the whole body as well.
3 Now if we put the bits into the horses' mouths so that they will obey us, we direct their entire body as well.
4 Look at the ships also, though they are so great and are driven by strong winds, are still directed by a very small rudder wherever the inclination of the pilot desires.
5 So also the tongue is a small part of the body, and yet it boasts of great things. See how great a forest is set aflame by such a small fire!
6 And the tongue is a fire, the very world of iniquity; the tongue is set among our members as that which defiles the entire body, and sets on fire the course of our life, and is set on fire by hell.
Matthew 12:34-37
34 O generation of vipers, how can you, being evil, speak good things? for out of the abundance of the heart the mouth speaks.
35 A good man out of the good treasure of the heart brings forth good things: and an evil man out of the evil treasure brings forth evil things.
36 But I say unto you, That every idle word that men shall speak, they shall give account thereof in the day of judgment.
37 For by your words you shall be justified, and by your words you shall be condemned.
Our feeling about a thing ought never to be the primary basis upon which we decide its moral quality. Being comfortable with using coarse, scatalogical terms doesn't mean using such terms is approved of God. As the verses above indicate, the speech of a disciple of Christ ought to reflect the holiness, purity, and grace of the Saviour, who is the Lord of that disciple's mind, heart and life (or ought to be).