"Practice like you preform it"
-band directors
"This isn't a practice, it's a rehearsal. Practice on your own time"
-band directors
"Don't suck"
-whoever to anyone
"Slow down" -- Response: "Grow some legs"
-tall people to shorter people

"the mediocre man is always at his best"
I'm not sure who said it but my bd quotes him often.

"So, uh, try not to suck too bad."

Drumline section leader said this to the underclassmen this year before the performance we always do for the parents.

Where I teach, we tell the kids, "You ALL SUCK, until WE say otherwise!"

Before a run through, my visual tech would say "Rock out with your c**k out" to the men and "Jam out with your clam out" to the ladies. Quite funny because it made us laugh till we got to our opening set.

"Lets turn the bass up on this one"

-as heard in the beginning of Rage Against The Machine's "People of The Sun"

When people started getting annoyed and yelling and crappy I said "HEY! Pretend you're eating sweet potato pie! Then maybe you'll chill out, 'cause everyone loves swee-tay-pa!." For the record swee-tay-pa is the correct pronunciation of sweet potato pie.

Also, for my fellow tenor before every show I say "Visuals or die" Because he always forgets visuals at practice yet magically manages to get them at every game.

I said this to my percussion section before a competition.

"Don't wait for your ship to come in. Swim out to it. A great performance tonight is the ship. Go get it."

The band took first place in our division and we took high percussion that night.

"You never know what the judge is looking for, all you can do is go out there and play your heart out and hope he loves it"

Our director usually says this before a competition. Or we have the awesome bass drummers who like to criticize people and bust out with the:
"do your basses have snares?"

My personal favorite this year hapens to be. "well that run was pretty darn good...but not GET YOUR BUTTS OUT THERE AND PREFORM THIS GOD DANG THING!"
of coarse that was censored to meet forum rules