99 plymouth neon - rattling on right side back rear of car?

if you,ll take a flash light and look under it you,ll probably find that either the muffler is coming down on it or it has broke a holder on it,its safe to drive only if its not going to come loose and cause an accident,make sure its not coming undone on it,because i have seen them fly from the bottom of the car and cause severe damage to the car they came from and also the car behind them,good luck with it.