What does "squeaky wheel" mean in slang?

Squeaky wheel in slang comes from the proverb the squeaky wheel gets the grease, meaning the person who complains the loudest or makes the most noise gets attention and gets their problem fixed. In slang, a squeaky wheel is someone who complains, whines, protests, or speaks up persistently about a problem until someone addresses it. It can be neutral or slightly negative depending on tone. In positive sense, it means being assertive and advocating for yourself, as in you have to be the squeaky wheel to get customer service to help you. In negative sense, it can mean someone who is annoyingly complaining or whiny, always making noise about small issues. In workplace slang, a squeaky wheel is an employee who constantly raises concerns or complaints. In politics, squeaky wheel groups are vocal minorities that get attention. The phrase implies that if you stay silent, you will be ignored, but if you squeak, you get oiled. So squeaky wheel means complainer who gets attention, sometimes admired for persistence, sometimes criticized for being annoying. It is not a swear word, it is an idiom about how complaining leads to action.