"The most impressive song that I can play on my tambourine is "The Flight of the Bumblebee," by Nicolai Rimsky-Korsakov [...]" (2-3)
When Oskar was at the craft store trying to figure out the significance of the word "Black" on the envelope he found, the person helping him says "Would you mind not shaking the tambourine in the store?" (46) before she leaves to help another customer. This is amusing as Oskar has evidently been playing his tambourine as he tries to think. Perhaps the music helps him to concentrate, or perhaps he is, like what is mentioned on page 88, keeping in mind who he really is as he as he tries to figure out what "Black" means; he is afraid of being pulled too far into the puzzle.
"I shook my tambourine the whole time, because it helped me remember that even though I was going through different neighborhoods, I was still me." (88)