Does he get an allowance? If so, he pays a dollar every time he uses one of those words. Keep a tally and at the end of the week he gets what’s left of his allowance. Don’t act shocked by his language, or make a big deal over it. — that’s likely exactly what he’s looking for. Just record it and calmly let him know you’re recording it. Expect him to test you with tantrums the first time he sees that you’re following through on the consequences. Remind him that how he spends his allowance is entirely up to him, and he chose to spend it on swearing. If he doesn’t get a rise out of you and all it gets him is lost allowance, he’ll get tired of it pretty quickly. Rewarding him with an emotional reaction will perpetuate the problem.