An omer is a measure of grain, in this case, barley. In the days of Temple worship, we were to bring the first sheaf of barley to the Temple, followed by other items, as a sacrifice (Leviticus 9–14).
In the game “Truth-or-Dare,” I choose “truth” nearly every time. I’m not much of a dare-taker. Thus, if you and I were playing “Special Edition Truth-or-Dare: High Holy Days,” I would confess that the prayer Avinu Malkeinu provides me with both my second-favorite liturgical moment and my second-greatest pet peeve of the year’s liturgy. (Note: Even though I may have to repent for it, I will leave you in suspense about my favorite liturgical moment and my greatest liturgical pet peeve. Also, “Special Edition Truth-or-Dare: High Holy Days” is fictional, although I hereby declare copyright in the event Mattel or Hasbro comes knocking at my door.)