At beauty pageants, contestants spend a great deal of time together. Some bond, others plot, but in the end they've taken a journey together none of them is likely to forget. So after the judges have had their say on who's the "best girl," the contestants get together for a final brunch or luncheon and vote for one of their own.
Being crowned Miss Congeniality is regarded as a great honor. Essentially, this means your beauty queen peers have decided that you are the most congenial: the nicest, most likeable, charming and respectable participant in the entire bunch. If that's not consolation enough for having lost the pageant, winners of the Miss Congeniality award can take solace in their cash prize and other gifts.