My wife + idioms = weirdness

I was telling my wife a story about how some boys tore down some class council election posters when my sophomore class took a walk around the building-- our periods are 83 minutes long, which is absurd, so I usually break it up with a lap around the school, but it's gotten cold so we had to walk inside, giving these three boys an opportunity to vandalize a rivals election posters-- and so I told my wife that I was no longer taking that class on walks because "the rotten apples spoil the bunch" and she started laughing and said she just realized that she butchered that exact idiom with her fifth-graders earlier in the day-- quite a coincidence-- she told her class that "the bad egg spoils the bunch," somehow combining the idea of a "bad egg" with the old Ben Franklin adage (which is actually "the rotten apple spoils his companions") but I explained to her that:

1) eggs don't come in a bunch

2) a bad egg doesn't spoil the rest of the eggs in the dozen because eggs have separate little compartments in the container and they are also insulated by a shell

and she found this logic so funny that she asked her class the next day if they noticed how she misused an idiom and a girl raised her hand and repeated my wife's distorted maxim back to her-- and my wife told the class that she really appreciated that no one corrected her and shamed her (as I often do) and then she told them about some of the other idioms she's butchered and she said the class was laughing so hard they were crying and one girl insisted that my wife was lying about these mixed metaphor mishaps but my wife told her that this was no exaggeration (and she believes this started happening more frequently twenty-five years ago when she got several migraines that were so bad that they thought she had a minor stroke and that this destroyed the idiom section of her brain-- but my theory is that she doesn't remember these phrases as single units, and instead substitutes synonyms for words within them at will, creating new phrases that are very close in meaning to the original saying).