In American slang, a "lemon" is a car that causes more trouble that it is worth, a second hand one for example. Other senses of 'lemon': - to buy or purchase a lemon means to buy something that didn't meet your standards,bad quality purchase. - In Australian slang, a "lemon" is a lesbian - In fan fiction, a 'lemon' is a scene or story that includes explicitly described sex.

"This car is a lemon"= this car does not meet the required standards. Australians say never to buy a car which was made on a Monday because the workers are still tired from the weekend and that you'll be buying a "lemon" As an Australian I have never ever heard a lesbian described as a lemon. A dyke yes, but never a lemon.

I'm not sure where this expression comes from, but it means that the car does not work. You would say that something "is a lemon" if it does not work very well. You usually use this term with something that you just received, and calling it a lemon implies that it is cheaply made, and therefore not meant to last or work for long.