Best Answer - Chosen by Voting
maybe its "snot"? :s
(a rich person has a handkerchief, he wears it in pocket
a poor man doesnt use it
and children usually put their finger into mouth after "cleaning" their nose with it) :))
PS. and i know another variant of the riddle like this one, but the answer is also the other:
the rich man needs it
the poor man has it
if you eat it, you will die...
