Try Not To Laugh!

The Prophet (Sallallahu Alaihi Wasallam) said, “The example of a good companion in comparison with a bad one, is like that of the musk seller and the blacksmith’s bellows (or furnace); from the first you would either buy musk or enjoy its good smell while the bellows would either burn your clothes or your house, or you get a bad nasty smell thereof” [Bukhari].