"Nova:" everybody unloads their dailies, typically during a boss fight. I'm sure this has been around for awhile, but seems to come up now more with 4th edition since the weapon users have abilities they can "nova" instead of just the spell casters unloading their moster powerful spells as soon as they can.
"Tap the Die" This one I've been told comes from the southern states (FL to be exact) during RPGA games. It means the PC knows the DC of the skill already and doesn't even need to roll it to make it ( ie Tumble checks or Concentration checks).