Posted by RRC on February 21, 2008 at 17:13:
In Reply to: Empty cans posted by Jenny on February 21, 2008 at 12:26:
: 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.