Beekissed
Mountain Sage
I think you'd be wasting some good mustard.
Yep...chickens, in spite of folk lore, don't really care about hot or spicy foods. They will eat hot pepper flakes like they ain't no thang.
And, once again, they would receive some lovely food when they pecked open an egg...it's almost like a positive reinforcement if one is trying to get them not to do so.