凡ミス

Meanings

1. Noun

   basic mistake; careless mistake

• トムはよく凡ぼんミスをする。

  Tom is careless and often makes mistakes.

• あぁ……、若わかかったとはいえ、しょうもない凡ぼんミスだ。

  Ahh ... well I was young but what a stupid mistake.