Why do you need a red shirt?

A navy captain is alerted by his First Mate that there is a pirate ship coming towards his position. He asks a sailor to get him his red shirt.

The captain was asked, “Why do you need a red shirt?”

The Captain replies, “So that when I bleed, you guys don’t notice and aren’s discouraged.” They fight off the pirates eventually.

The very next day, the Captain is alerted that 50 pirate ships are coming towards their boat. He yells, “Get me my brown pants!”