While on patrol, the Enterprise encountered a Klingon warship who tried to board the ship. The crew was worried, but Kirk was calm.
He turned to his yeoman, "Bring me my red shirt!"
The yeoman quickly got the Captain's red shirt, which the captain put on. Then he led his crew into battle against the Klingons. Although there were some casualties among the crew, the Klingons were defeated.
Later that day, the conn noted that there were two klingon vessels sending two boarding parties towards their ship. The crew was nervous, but the Captain, calm as ever, bellowed, "Bring me my red shirt!" And once again the battle was on!
The Captain and his crew fought off the boarding parties, though this time more casualties occurred.
Weary from the battles, the men sat around in the rec room that night recounting the day's events when an ensign looked at the Captain and asked, "Sir, why did you call for your red shirt before the battle?"
The Captain, giving the ensign a look that only a captain can give, explained, "If I am wounded in battle, the red shirt does not show the blood, so you men will continue to fight unafraid." The men sat in silence. They were amazed at the courage of such a man.
As dawn came the next morning, the conn screamed that there were Klingon ships, 10 of them, all with boarding parties on their way. The men became silent and looked to the Captain, their leader, for his usual command.
The Captain, calm as ever, bellowed, 'Bring me my brown trousers!!!'