Hey, it's more effective than "Please stand clear of the doors."

Train conductor (in smooth announcer-type voice): "Blue Line...Largo Town Center..."

(switches voice to yell at someone holding the train up)
"Girl! Git out tha doorway! You holdin' me up. I ain't got all day!"

(back to announcer's voice) "Blue Line...Largo Town Center..."

-Blue Line at Pentagon City Station