"I put coffee grounds in the tank of the toilet in my mom’s bathroom. Basically, when you flush, the toilet will fill with brown water (which is usually an indication of a burst pipe). I heard the toilet flush and mom came running out of the bathroom in a panic."
If it is really old and rusted pipes it can happen randomly, but typicaly after peaking pressure that will rattle the dirt in the pipes loose. Reconstruction where the pipes are knocked can also do this.
I don't think mom actually immediately thought of the exact cause, people...
She just thought something was obviously wrong which was the whole point. Best to move on, future plumbers.