Ruby's Wish...peanut butter

I was reading Ruby's Wish to the class one day. It's about a young Chinese girl who wants so badly to go to "the University". Later in the story, she's at a Chinese celebration where everyone gets a red envelope that is usually filled with money. Ruby's envelope was thicker than usual. I asked the students to predict what was in the envelope.

Student 1: I think that it's a big wad of money.
Student 2: It's probably confetti.
Student 3: Maybe it's money to go to the University.
Student 4: I think that there is peanut butter inside.

....On that note, I continued reading the story....
"It wasn't money...", I read.
All of the students who guessed money said "Aw, man!"
Student 4 responded, "It must be peanut butter."