"He started crying not out of happiness, i could tell, but not out of sadness either. Are You Ok? I whispered. The sound of my voice made hi cry more, and he nodded his head yes."
In the conversation between Oskar and his mom at the end of the book, Oskar's mom succumb to tears: "She nodded yes, and it was the first time since Dad died that I'd seen her not try to stop her tears. Was she relieved? Was she depressed? Grateful? Exhausted?" This shows that tears can mean alot of different emotions.
At the end of the book, Oskar goes back to see Abby Black because she knows something about the key she says. Oskar becomes very upset and frustrated with himself and his extremely prolonged search and begins to cry.
"maybe its true that you can use up all of your tears. Maybe Grandma's right about that. It was nice to think about, because what I wanted was to be empty." (290)
Oskar is sick of all of this emotional baggage and wants to just be done with it. In a way I feel like he wants to "take off his heavy boots."