question that many today might consider too "negative," "O generation of vipers, how can ye, being evil, speak good things?" We saw that a good man out of the good treasure of his heart brings forth good things, but an evil man out of the evil treasure bringeth forth evil things" (Matt. 12:25). That includes the "four-letter-words" that are all too often used today, even by those professing Christianity.
Jesus warned in Matthew 12:36, "That every idle word that men shall speak, they shall give account thereof in the day of judgment." This includes more than just four-letter-words. Paul urges "Let no corrupt communication proceed out of your mouth..." (Eph 4:29). That would include, lying, "dirty" jokes, gossip, etc.! He gives a far better alternative in Colossians 4:6, "Let your speech be alway with grace, seasoned with salt, that ye may know how ye ought to answer every man." And, "but rather giving of thanks" (Eph. 5:4). James gives an additional alternative in James 5:12: "...swear not...but let your yea be yea; and your nay, nay; lest ye fall into condemnation."
Apologies to preachers and other Christians are good, but, these truths apply to everyone, no matter who the audience is.