“What about 'The Nostalgia Police'?”
You and a few friends are starting a band and trying to think of a name for the band. This is your suggestion.
What about 'The Nostalgia Police'?
This is the phrase you use when you're listing suggestions for something. When you're trying to come up with names for something, each person will make a suggestion by saying "What about ___?" Then the group will discuss whether that's a good idea. A few minutes later, someone else will say "Well what about ___?"
Bands usually want a name that sounds unique, so band names in English are often strange collections of words that don't make sense together. "Nostalgia" is the feeling of wanting to return to the past, or having good memories of an earlier time in your life. So "nostalgia" doesn't make sense as a type of police.