Rusty may be a modern-day pre-teen, but he grew up in Lost Forest; so animal sounds should not be mysterious or unsettling to him (as seen in panel 2 with that Pokémon inspired back design). He’s pretty jumpy, in fact! Was the sound really unusual or out of place in the forest?  The sound effect (“Krack”) is something normally associated with stepping on a small branch and breaking it. So, nothing too unusual. From what I’ve read, raccoons don’t seem to be too concerned with making noise as they move about or hunt. Still, I suppose it beats meeting up with a mamma bear and her cubs. I just hope this little incident will not break Rusty’s spirit and send him packing, back to the scout meeting.