These guys are mad, but I just call their all-ins when im sure i have a pocket high, like JJ+. They usually do these things to steal bets, so if u call, is probable that he wont have higher cards that you, but be careful cause sometimes the flop can hit his pair or triple and you lose. So just wait till you have a good solid hand to call, but even with strong hands is up to you wheter calling or not, cause sometimes it's better to wait for the correct time to play a good hand with the other non-mad players than wasting time and money with these crazy donkers.