My Mimi girl does the feet attacking/ play biting thing too. Especially when I'm wearing the fuzzy slippers. She just goes right in & takes a big chunk of toe & slipper in her mouth & she doesn't let go. I usually just slip my slipper off (it might be hard to do w/ shoes) & she let's go. Maybe you can try that w/ slippers & when they let go, give them a treat. Soon, they'll associate letting go of slipper/feet = treats! But what if they keep attacking feet just to get treats?!