In Margaret Talbot's thoroughly interesting New Yorker piece on why so many evangelical teenagers are having sex, there's this nugget about teens who pledge abstinence:
…in some schools, if too many teens pledge, the effort basically collapses. Pledgers apparently gather strength from the sense that they are an embattled minority; once their numbers exceed thirty per cent, and proclaimed chastity becomes the norm, that special identity is lost.
Fascinating. Underdog status really does matter.