Use in any situation when saying what you really think would be a mistake.
The silent knobhead works in the same way as the 'magic e' or split digraph, as adding it at the end of a word or sentence changes the sound and meaning of the rest of the phrase. It results from implied use of the word knobhead at the end of a sentence, without actually saying it, thus changing the meaning of the sentence. The benefits of using the silent knobhead are that your conversion should be able to continue without the other party realising that they have been insulted, therefore maintaining and protecting relationships, for example with family, friends of friends, or colleagues.
Nannette: Oh my god, did you hear what Christian said to me? He must really mean that he wants us to be friends if he's offering me a massage after the gym!
Fleur: Yes, of course he does. He's probably interested in you for your mind (silent knobhead)!