The names of some foods have rich, colourful histories. Mayonnaise was reportedly created in 1756 for Duke de Richelieu after his heroic victory at the Battle of Port Mahon. Both avocados and vanilla have off-colour histories related to the salty senses of humour of the Spanish explorers who named them.
Some, like sirloin, are not so exciting. The name just means 'above the loin'—pretty boring, I know. So boring, in fact, that amateur etymologists saw fit to concoct the following story (using the ancient art of 'Making Stuff Up'):
King Henry VIII was a notoriously eccentric monarch, and a man who loved a good piece of steak. I mean, look at the guy! This was one English nobleman who could appreciate a good meal. So deep was this appreciation, that, after a particularly amazing piece of beefsteak, he saw fit to dub his dinner as a knight of the realm. Thereafter, this delicate and tender cut of meat has forever been known as "Sir Loin."
One of the most tender and flavourful cuts of beef, sirloin is a prized steak. It hardly needs a royal pedigree to be a terrific meal.
I heard the Henry VIII myth, presented as truth, in my grade-school years. It's been debunked in dozens of books (including, I believe, Dave Feldman's "Who Put the Butter in Butterfly?").