At 18, it's called High School Graduation. Probably the only near-universal item on this list.

At 16, it's called getting a driver's license.

As far as 11/12/13 year olds go, there are several ceremonies, none universal:

Bar Mitzvah
Cub Scout/Boy Scout crossing-over ceremony
Elementary School graduation
First school dance
Getting kicked out of the Burger King Big Kids' Club
Paying adult prices at restaurants (IMHO they should charge hungry teens MORE, seeing how much they eat :) ).

I'm sure there are many more examples.