Unimportant, irrelevant, as in You pay for the movie and I'll get the dinner check, or vice versa—it's neither here nor there. This expression was first recorded in 1583. Also see beside the point.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use neither here nor there in a sentence
We are introduced successively to the Palestinian, the Assimilator, and the Neither-here-nor-there.
Swinburne dismisses him in two lines: Maximilian is a good-natured, neither here-nor-there kind of youth.The Life of Ludwig van Beethoven, Volume I (of 3) | Alexander Wheelock Thayer
The neither-here-nor-there expression still rankled in Gizzard's memory, and now Sube was adding vinegar to the wound.Sube Cane | Edward Bellamy Partridge