This is a "made up" term used on the popular Trinidadian, automobile website to determine who really knows about cars. Cars do not carry muffler bearings.
Contrary to popular belief, muffler bearings do exist, just ask your local dodge stealth or mitsubisi gt3000 owner. Although a popular prank to pull on the not so automotive savy muffler bearings are located inside the muffler, in order to operate a flap which opens and closes depending on the exhaust flow directing flow back into the turbo. Due to inconvienience (carbon/other buildup often jammed the bearings causing noise and poor performance) the bearings are only found on older models.
Hey go into the garage and grab the blinker fluid and spare muffler bearings!
A real howl for prank-calling kids of our 70's past: get a naive auto parts clerk on the phone (dumb teen, etc.) and ask for "muffler bearings". A bigger howl when they realize the gag, and get back on the phone and cuss you out.
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.