Dakka
Ork slang for rapid fire capability, based on the onomatopoeia for for the sound of automatic guns shooting. You need more of it. No exceptions.
When other races use it, it's just not cool anymore. Must have something to do with that rockin' Ballistic Skill 2 that da Orks are throwing down.
Exception: Dakkafex=SICKHOUSE
According to the Ork color wheel, painting a weapon yellow will give it more dakka.