The phrase "go byes" is not commonly used in modern English. However, it may be intended to convey the idea of going to sleep or going to bed. Some synonyms for this phrase could include "hit the hay," "retire for the evening," or "turn in for the night." Other options might include "doze off," "drop off," or simply "go to sleep." Depending on the context, there may be other appropriate phrases or idioms that could be used to express the same idea. Ultimately, the best synonym for "go byes" may vary depending on the speaker's intention and the specific situation in which the phrase is being used.