I Heard some people eat monkey brain and crocodiles? is that true in some countries?

I don't think people eat monkey brain anymore. Alligators are consumed as food in many countries, including in the United States.

Enjoy your burgers and don't ask what's in them.

I would think that it is true;
some Orthodox Asian Indians think us barbarians,
as we devour cows..which are sacred to them.
People who are under - resourced will eat what is available -
the the wealthy, or corporations get wind of it all and make it into an expensive `delicacy`,
which is then beyond the financial reaches of the under - resourced,
and
often until the animal becomes an endangered species. The poor generally stay poor.