The three little musketeers, Luke, Jericho [Malabonga] and Henry** [Nicholson], decided to steal the rest of the jam one night and then flat out lied about it the next day. The inside joke between the trio was hilarious to watch - they were like teenagers trying (not very well) to keep a big secret.
When Jericho got a secret jar of cookies, he could have hidden them for himself and not shared with anyone. But his bromance with Luke was too strong so he pulled him into his cookie crew. When the two of them were eating the sweets late at night while the rest of their tribe slept, the two of them plotted to sprinkle cookie crumbs over people's pillows to mess with them. So. Brilliant.
Luke made a secret spot near the water well so that he could overhear his tribe mates talk strategy. Covered by trees and branches, Luke would lay down like a total creeper and spy on people for his own advantage. It worked well for him when he heard Tessa plotting against him, which then led to her getting the boot at the next tribal council.