"Wow, we were in the tree house a long time." Chris said as the boys got closer to the house.
Even from the outside Shawn could hear and feel that things were different from when they left. First, the inside of the house was teaming with silhouettes--house guests that had arrived for the Halloween party and passed through the lighted windows. Shawn couldn't distinguish their features, but the fact that they were so many indicated that the house was packed.
Second, and perhaps more surprising, was the loud music that must have been blasting from inside the house. Michael Jackson's Thriller was playing so loud inside the house, that Shawn could distinguish the lyrics and feel the muffled vibrations of the music.
https://www.youtube.com/watch?v=xIx_HbmRnQY