You clever devil!

Last night I made an awesome faux pas in Spanish. My mom's family was gathered at her house to celebrate her birthday. Dinner had been eaten, presents opened, cake served. I was massaging my grandmother's shoulders, as she had some big knot that was bothering her. The conversation was all in Spanish, so don't be confused by my switching between Spanish and English in the transcription that follows: it serves a [humiliating] purpose.

Me: Wow, Mama [that's what we call her], that's a big knot!
My mom: Don't say that, you'll scare her!
Mama: [Laughs weakly]
Me: You might need to go to the doctor!!
Mama, et al: [Laugh]
Me: ¡Créo que vas a necesitar cesaria!
Everyone: [Laughing hysterically]
My mom, in English, for the non-Spanish-speakers: She said the knot is so bad she's going to need a C-section!
Me: Um... ah...
Everyone: [Laughing]
Me: I meant to say cirugía!!!
My mom, in English, crying with laughter: She meant to say "surgery!!!!"

Much blushing ensued. I ought to be used to this by now, no?