Putting a toilet paper roll in the toilet is a failure of waste management. It is a rigid, semi-solid object that plumbing systems are not designed to handle. While it might slip down the pipes once by sheer luck, repeated attempts or catching it at a wrong angle will result in a backed-up sewage line.
: The cylindrical paperboard core is not meant to be flushed and can easily jam in the P-trap, the sharp turn in the toilet pipe where clogs most often occur. toilet paper roll in toilet