The best movie of the genre is Steven King's Stand by Me. But the second best, by far, is Kings of Summer. If you had trouble with your parents growing up, this is a MUST movie. If not, you still mike like it even though the language and such can be a bit raunchy.
IMDb Link for Kings of Summer: http://www.imdb.com/title/tt2179116/?ref_=nv_sr_1
IMDb Link for Stand by Be: http://www.imdb.com/title/tt0092005/?ref_=fn_al_tt_1