It ALWAYS happened. Kirk, Spock, Bones, and an Ensign Smith would beam down to a hostile planet. Guess which one ALWAYS got killed?
And, they always wore a red uniform, hence the term 'red shirt' which is now used throughout the TV industry to denote the guest star that is killed off during the episode. In one of the recent episodes of "LOST", a character Boone even brought up the term and explained what it meant to another character as they were traipsing through the jungle.
Then they could say "They killed Kenny, those ___________ b@#$%ds"