It can also be used when two people say the same thing at the same time.
Vixter- "Lets watch Kenan and Kel"
(Both together) "Boom-Boom"
Obviously not handsome man: "How much sweetheart"?
Me- When I was in Minnesota, I got all excited because I heard a girl refer to something as ' Boom Boom ', I asked where she heard it......... She said back home in Tampa. So no, I don't believe so.
Random friend that came over for some cake mix ketchup-Chick! Denise over in Town N Country said 'Boom Boom' the other day!
Me- She just moved there after living in Tampa for 6 years.
He and Little Sister in unison - DANMIT!