Prove It to me

Bhola goes to a grocery store. He finds cat food at special prices. He picks a dozen cans of cat food and goes to check out. The Manager gets suspicious. He thinks that this guy cannot have a cat and will probably feed cat food to his kids. He asks Bhola to show him his cat before he could let him have cat food. Bhola goes home and returns with a cat and gets to buy the cat food.
 
Next week Bhola finds dog food at special prices. He picks a dozen cans of dog food and goes to check out. The Manager again gets suspicious. He thinks that this guy has a cat but he cannot have a dog and he will probably feed dog-food to his kids. He asks Bhola to bring and show him the dog before he can let him have dog food. Bhola goes home and returns with a dog. He gets to buy the dog food.
 
Next week Bhola comes to the grocery store with a bag. He asks the manager to put his hand in the bag. The Manager puts his hand in the bag and immediately takes it out. He shouts at Bhola: "What! This is shit!"
 
Bhola calmly replies: "Yes, and this is because I want toilet paper"