The phrase "went fifty-fifty" means that two parties shared something equally. The opposite of this phrase would be a situation where one party gets more than the other. Antonyms for "went fifty-fifty" include words such as unequal, unfair, unbalanced, lopsided, and disproportionate. For instance, if someone were to say, "I got the entire bonus, and my colleague got nothing," that would be an example of a situation that is the opposite of "went fifty-fifty." It's essential to use the right words to convey the intended meaning accurately, which is why antonyms are helpful in understanding the concept.