Unfair, unsportsmanlike, as in It's not cricket to let him go without notice. This term, in which the sport of cricket is equated with upright behavior, survives in America despite the relative unfamiliarity of the sport there. [Mid-1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.