1. In a state of physical or emotional exhaustion, especially such that one cannot think or react properly. I was so whacked out after that 12-hour flight that I had trouble following along with what people were saying to me. We were all a little whacked out by the time we got home from the marathon, so we just showered and went to bed early.

2. Intoxicated from drugs or alcohol, especially to the point of incoherence or belligerence. Tom was so whacked out at the party that he couldn't speak properly by the end of the night. No thanks, I don't like how whacked out I get when I smoke weed.