The phrase "starting with an X in the corner say..." has several potential origins and interpretations, making it a fascinating linguistic and cultural puzzle. Here's an exploration of the most common possibilities:

1. Children's Learning Aid

The phrase is likely connected to traditional alphabet games and children's educational tools.

• Mnemonic Device – It might act as a simple memory aid to help recall words starting with "X." For example, "Starting with an X in the corner say... xylophone".

• Visual Learning – Classrooms might've used charts or posters featuring objects starting with "X" arranged in the corners to reinforce letter recognition.

2. Reference to Cross Stitch or Embroidery

• Craftsmanship – Cross stitch and embroidery patterns frequently begin at the corners. The phrase could be a needlework instruction: "Starting with an X in the corner, say... cross-stitch this flower."

3. Navigation or Map Reading

• Coordinates – In older navigation systems, maps might have been divided into sections with corners labeled by letters. The phrase might be part of direction-giving: "Starting with an X in the corner, say... which route is the shortest?"

4. Wordplay and Riddles

• Linguistic Humor – The phrase's odd construction makes it a potential candidate for a riddle or a playful joke. The purpose might be simply to cause confusion or amusement.

5. Obscure Cultural Reference

• Lost in Time – It's possible the phrase originates from an outdated regional saying, a children's game no longer popular, or an inside joke within a specific group. Its true meaning might be lost or forgotten.

References

While there's no single definitive source for this phrase, here are some places where it or similar expressions have surfaced:

• Wordnik - Questions about X in the corner: 
• The Phrase Finder - Say X for yes: 

The Mystery Continues

The incomplete nature of the phrase "starting with an X in the corner say..." adds to its mystique. If you have any other theories or remember encountering it in a specific context, please share!