Needle in a haystack

It's the most dreadful roadblock task in the history of TAR. Unrolling hundreds of hay bales to find one of seven flags hidden. You need luck, and there's no other trick. You need to be lucky to find the bale with flag hidden inside, and you will never know it's the wrong bale until you spend all your time and energy unrolling it.

If we were ever to face this challenge, you have to be the one doing it, because I have no luck.