Knobbing is a slang term that refers to having sexual intercourse. It is considered offensive in many contexts and should be avoided. There are several synonyms you can use instead of knobbing to avoid using inappropriate language. These include sleeping with, bedding, making love, having sex, hooking up, or consensual coitus. Using these terms will not only prevent you from offending others but will also help you communicate your ideas more effectively. Remember, it's essential to respect others' boundaries and use language that is appropriate for the situation.