What did Bud have to promise to tell Herman after eating?

Bud had to promise Herman that after eating he would come clean and tell the truth.

"Once you get something in your belly you've got to be straight with me, you've got some explaining to do, we'll feed you but you've got to tell us the truth. Do we have a deal?"
He stuck his hand out for me to shake. But I wanted to know what I was getting myself into.