This is quite an old phrase, dating back to WW2 at least. To "get a rocket" is to be scolded or told off, usually by someone in authority; boss, manager, teacher, parent, etc. It may go as far as dismissal.
by New Old School January 03, 2012
A term used when the funnist kid in the world, Joeseph White, says when he makes fun of English people in Halo 2.
by Steven Levy December 17, 2004