Based on the context and the answer, generate a question. 

Context: She would do it sometimes when I opened the fridge door or whenever she heard the sound of a bag being crumpled ( thinking she was about to get hay or lettuce ! ) . Now I open the fridge door and automatically I am waiting to hear her , but I do n't hear a thing . Except like just tonight , I heard her .

Answer:

Their pet is hungry .



What may be the reason for hearing their pet when they open the fridge door ?