When you're trying to write something funny, it has to be an idea that first strikes you, personally, as funny. The reason for this is that, then, it's something you're genuinely amused by. When this is so, it's based on observation of an experience that others may relate to. The next step, after this, is to try to translate it for others to understand. Sometimes you can't reword it perfectly for others to appreciate because the words themselves carry different notes of meaning to you. Nevertheless, the aim is to try to keep your audience's jargon, their palette of words, in mind.