Sir Gawain swam his horse across the river. They jousted. The knight demanded Sir Gawain battle on foot. Sir Gawain agreed. "I must know your name," Sir Gawain said. "I am Erwin of the Three Rivers," said the knight. Sir Gawain beheaded him with one stroke of the sword.
In fact, telling somebody your name is much like wearing a red shirt in the Star Trek universe: