What does "time flies" mean?
When we are busy and having fun, our brains perceive time passage differently. Hence the expression time flies.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.
### Instruction: What does "time flies" mean?
### Input: 
### Response: When we are busy and having fun, our brains perceive time passage differently. Hence the expression time flies.