No. I often use it when I feel stuffy because sb's behavior is very stupid. It can be used various situation. most of all likely have negative meaning. Shortly, there are two main means. one is to emphasis to express your funny feeling. When you see a funny movie and you feel It is very funny then you can use 미치겠다 (웃겨서) but It is very important to makes your face laugh. If you not, it would be very sarcasm. two is the negative meaning. when you ordered to your friend to do someting and time was over. but your friend done nothing. In this situation you would feel stuffy and could say "아 미치겠네 진짜" Yes.. logically thinking, If the situation keep going, you could be crazy. but It is nonsense.