They gave it a good shot! For failing to make the Philosopher's Stone, Tonbokiri and Keigo will find that any food they touch will turn into a stew consistency. For a week, no matter how hard they try, the food's going to become something soupy and stewish. Apples will become apple-saucey, chicken will suddenly be as though it was slow boiled in stock for hours and hours, and potatoes will become a very watery mash, for example.

Not in a bowl, mind you, just in their hands. Hopefully they figure out fast to carry a bowl around with them every time they want to eat.

This effect will last for a week for both of them!