I must clarify that "muffler bearings" are actually a fictional and humorous term that originated as a joke or a prank. They do not exist as real components in vehicles or any other machinery.
The term "muffler bearings" is often used to playfully tease or trick someone who may not be familiar with automotive or mechanical terminology. It is similar to other made-up terms like "blinker fluid" or "elbow grease," which are used in a similar humorous context.
So, in short, muffler bearings are not real parts, and they do not serve any actual purpose in vehicles or machinery. They exist purely as a joke or a prank.