Empty cans

Posted by Pamela February 21, 2008 at 23:43:In reply to Empty cans posted by RRC on February 21, 2008 at 17:13:

What does this mean "two empty cans make a lot of noise"?

The phrase has many variations but it is usually just about "empty cans" not "two empty cans".
Empty cans make the most noise.
Literally, if you hit a full can with a spoon, you get a dull thud, but if you hit an empty can, it may ring like a bell. Metaphorically, people who don't know much (empty cans = empty heads) often are very vocal with their opinions, complain a lot, etc.

"Empty vessels make most sound" is the version I've heard, with the same meaning. Pamela