Very versatile it can be used in many ways to insult someone. By referring to someone as a lemon you are calling them a dickhead, weird, slow, lame, and most of all corny. Really depends on the context.
âThis ni**a wear Balenciaga with boot-cut jeans heâs a fucking lemonâ
âI forgot to take the meat out the freezer Iâm such a lemonâ