A quote from one of my Drill Sergeants that has always stuck with me:

“Just when you think they’ve got something foolproof, they have to go and invent a better fool.”

Said to me through a facepalm as we watched a private plant a claymore mine facing the wrong way… and for anyone unaware, the claymore mine literally has the words “back” written on one side and “front towards enemy” written on the other.

Edit: fixed spelling