Waste of time
Ok..so lets wiseacre for a bit..
and realize that time is relative.
We all experience it differently and at different times of the day. Speaking of daytime, we have that due to the earth rotating on its axis. Daytime would be different on another planet (if it had a sun or maybe more then 1 sun, its rotation speed etc..). In fact that is how we measure time. By our revolutions on an axis and around the sun. These measurements are arbitrary. You can make up your own system of time and if it starts to become adopted on a widespread scale, then bam, you have a new concept of telling time.
Now how can you waste time?