"its a four letter word. Boys have, girls dont. Porr have, rich dont. You can fly if you have it. Animalas can drink dut we cant. what it?"
I think the answer is: BOYS
Boys =B. Not in ?'girls'.
bOys =O. in pOor - Not in ?'rich'.
boYs =Y, in flY - if you have it. Otherwise it would be 'fl'
boyS =S. in animalS. (You need ?'s' for more than one animal to drink). Not in ?'we' or ?'cant'.