Whacked is a colloquial term used to describe someone who is exhausted or extremely drunk or high. There are several synonyms that can be used interchangeably, including spent, drained, worn out, fatigued, and knackered. These words all convey a sense of depletion, and are commonly used in a variety of contexts, such as after a long day at work or after completing a strenuous activity. Additionally, whacked can also be used to describe someone who is out of touch with reality, such as someone who is delirious or inebriated. Synonyms for this usage might include addled, befuddled, or disoriented. Regardless of the context, there are many words that can be used in place of whacked to accurately convey a sense of exhaustion or disorientation.