This is an American proverb used to convey the idea that the most noticeable (or loudest) people are the ones most likely to get attention and resources. Someone else or another issue might be more pressing or in dire need, but the fact is that the noise makes it impossible to ignore the squeaky wheel. The people that complains or protests the loudest attracts attention and service.
It is also used in the variant of “The squeaky wheel gets the oil”.
Other cultures have similar proverbs that express the same sentiment: The Chinese say “会哭的孩子有奶吃: The crying baby gets the milk”; The German, similar to the English, say “Das Rad, das am lautesten quietscht, bekommt das meiste Fett: The wheel that squeaks the loudest gets most of the grease.” and the Spanish say “El que no llora no mama: He who does not cry does not get breastfed.”
The proverb was popularized by the American humorist Josh Billings, who used it in his putative poem “The Kicker” (c. 1870).
I hate to be a kicker,
I always long for peace,
But the wheel that squeaks the loudest,
Is the one that gets the grease.
The first publication of the poem can be traced only to 1910. For unknown reasons, in 1937 Bartlett’s Familiar Quotations attributed the poem to Henry Wheeler Shaw, whose pen name was Josh Billings.