Before you can make fun of anyone or anything else, you need to be able to laugh at yourself. Without that ability, you may come across as a bully. So start with self-deprecating humor.
Everyone has something weird about themselves. If you’re short, you can make a crack about escaping Willy Wonka’s factory. If you’re a video game geek, you can say that you prefer to wear a Tanooki suit on dates. Feel free to point out your snort-laugh, chuckle at your tallness, or even just laugh at the sound of your voice–just something silly and uniquely you. Don’t beat yourself up, though–your idea isn’t to drill your flaws into your head, but to sort of embrace them as what makes you who you are, so others will see them the same way.