You're not screaming at me! I can't hear you, [unintelligible]. Recruit: Aye, aye, sir! Aye, aye, sir! Aye, aye, sir! Aye, aye, sir! Narrator: This is Marine Corps boot camp in Parris Island ...

Recruits: Yes, sir. Drill instructor: Or that butt stroke. Scream aye, sir. Recruits: Aye, sir. Narrator: A key aspect of their martial arts training is fighting with pugil sticks. Drill ...