Jumping out of the tree was forbidden to younger students at Devon, such as Gene, Finny, and the others. Senior students jumped out of the tree as part of their preparations for the inevitable military enlistment that awaited them after graduation, but the tree was supposed to be off-limits to underclassmen. So, the first enticement that marks many rites of passage - breaking the rules - was met.
Once Finny jumped, Gene reluctantly followed because he was already willing to follow Finny's leadership. "What was I doing up here anyway? Why did I let Finny talk me into stupid things like this? Was he getting some kind of hold over me?" The meeting of peer pressure marks many rites of passage.
As the two initial jumpers, Finny and Gene achieved instant status - they were the only members of the club, and they reveled in the unspoken admiration of the others who weren't brave enough to join the "jumpers" at that time. "He and I started back across the fields, preceding the others like two seigneurs" - two men of rank or high status.
A Rite of Passage marks the achievement of some accomplishment that is noteworthy, at least in the eyes of ones' peers. Becoming a member of the Super Suicide Society was such a feat.