soo..i was at the local petstore checking out their selection and i overheard the salesperson telling a customer to add ammonia rocks to his tank to bring down the ammonia levels? what is this all about?

Could be talking about ammo chips, or zeolite, a mineral which will remove ammonia from the water, up to a point. Salt in the water will cause zeolite to release its ammonia back into the water, and it can be recharged this way.

If they are used in a cycled or cycling tank, there will be no ammonia available for the beneficial bacteria to use, causing the cycle to crash.