Is a crock pot made of rocks? Asking for a friend. ?

A 'crockpot' is a brand name for an electric 'slow cooker'.
The name derives from the old 'crocks' with lids that were made from earthenware, they ware used on and in stoves to cook stews e.t.c. 

Tell your friend "yes".

No, but you Can cook rocks in one. 

Sort of. It's clay.