Who's the dummy now?

Major Payne:
[the cadets are running an obstacle course in heavy rain]
LET'S MOVE IT, YOU TURDS! You'll get no sympathy from me! You want sympathy, look in the dictionary between shit and syphilis! That's where you'll find my sympathy! This ain't no walk in the park; let's go! Hustle, HUSTLE! HUSTLE! [Woliger has just gotten out of the tube] Major Payne:
Yo, Dumbo! You should be able to fly through those tubes with them big-ass ears, boy! [Dotson laughs] Major Payne:
WILLIAMS! You tell Marlee Matlin's son to get across that rope before I hang him with it! [Dotson yowls with mirth] Major Payne:
HEATHCOAT! Get your side-of-pork booty over that wall! fat body up over that wall, or I'll... [notices Dotson guffawing] Major Payne:
... SHUT UP OVER THERE! [Dotson snaps to it] Major Payne:
Nobody's leaving here until you turds get this course down to EIGHTY SECONDS! Cadet Alex Stone:
[breathing very hard]
Come on, he can't do this; leave him alone. *I* can barely do it. It's slippery out here. Major Payne:
Slippery, you say! You think Charlie cares about slippery? Only thing he cares about is slitting your throat! WHAT IF THIS WAS A LIFE-OR-DEATH SITUATION? Cadet Alex Stone:
That's just it. This ISN'T a life-or-death situation. [Payne whips out a hand grenade and pulls the pin with his teeth] Major Payne:
IT IS NOW! [All the cadets, including Dotson, scream in horror while bolting through the obstacle course. Alex, however, just stands where he is] Cadet Alex Stone:
Come on, guys! Relax, it's just a dummy grenade! [Payne throws the grenade, which explodes and fells a defenseless tree. Alex dives for the nearest cover... a mud puddle] Major Payne:
Who's the dummy now?