Guys do appreciate a partner who can laugh around and joke with them. They would appreciate some casual leg-pulling and playful teasing. They wouldn’t generally mind if you are laughing at him too. But, it truly depends on what aspects about him are you laughing about. If you are pulling at some insecurity of him, that certainly will not go down well, especially if he has told you what he is insecure about.  Nobody likes to be around with someone insensitive. Be funny without being mean. Kindness should always be of paramount importance even if you are trying to win him over by trying to be good at sarcasm and jokes.