What does “mebachiko めばちこ” mean?

“Mebachiko” is a casual Kansai term for what’s known in standard Japanese as “monomorai”, or a stye—a red, painful bump on the eyelid.
Although it’s widely used in the Kansai region, many people outside of Kansai may not recognize the word at all.
It’s a great example of a local expression that’s still going strong in daily use, even if it sounds unfamiliar to the rest of Japan.
You might hear someone say it naturally when they suddenly get a stye, like:
“Ah, I got a mebachiko again…”