Wiktionary
waste of time
n. A meaningless or fruitless activity.
WordNet
waste of time
n. the devotion of time to a useless activity; "the waste of time could prove fatal"
Usage examples of "waste of time".
I obey orders, and if you're to be tested, you'll be tested, waste of time or no waste of time.
He called the wall a waste of time and effort, and perhaps it was, but it made her teeth chatter.
I fear talking to them is a waste of time, but if you must talk, let me ring their position openly with steel so they know the price of putting a foot out of line.
I told you this morning that I knew perfectly well this patrol was a waste of time and effort.
Weiramon did not care whether they had their throats slit, but he considered torture a waste of time.