There are several synonyms for the phrase "flaked-out" which can be used to describe someone who is exhausted or overwhelmed. These synonyms include "burnt out", "worn out", "spent", "fatigued", "done in", "drained", "knackered" or "exhausted". Each of these words conveys the feeling of extreme tiredness, where the person simply cannot go on any longer. Whether it is due to working long hours, dealing with high-pressure situations or simply feeling overwhelmed, these synonyms can be used interchangeably to describe a person who has reached their limits and needs to rest and recharge.