The biggest knight at King Arthur's round table was Sir Cumference. He acquired his size from eating too much pi.
Why this joke works
Sir Cumference Meets Pi
“Sir Cumference” sounds like circumference, the distance around a circle, and the Round Table supplies the circular setting. Pi is the mathematical constant used to calculate a circle’s circumference, while “pie” is food that could make someone larger if eaten excessively. The joke combines a knightly title, geometry, and food in one chain. Each clue reinforces the same circle theme rather than serving as an unrelated medieval decoration.
A closer look
Each sentence completes a different circle
The first sentence turns a measurement into a knight's name, using “Sir” as the hinge. The second explains his size through another sound-alike, “pi,” while connecting that constant back to circumference. King Arthur's Round Table keeps both moves inside one circular image. Let the two sentences breathe separately: listeners can solve Sir Cumference first, then discover that the food explanation is also mathematical rather than random.
Fact behind the joke
NASA uses pi without needing endless digits
Pi equals a circle's circumference divided by its diameter and has a decimal expansion that never ends or repeats. Although it has been calculated to trillions of digits, NASA says 3.14 is often precise enough for ordinary work and far fewer digits than the known total are needed for missions. Engineers use pi for circular areas, planetary volumes, spacecraft paths, and parachute sizing—real calculations worthy of Sir Cumference's name.