せえの

せえの, せいの, せーの, いっせいの, いっせーの, セイノーseeno

interjection

  1. all together now!
  2. one, two, go!
  3. ready, set, go!
  4. heave, ho!
  5. oops-a-daisy

Study it in Yanamino

Data from JMdict, KANJIDIC2 (EDRDG), KanjiVG, CC-CEDICT and Make Me a Hanzi. Sources and licences