That didn't sound like "bye-bye"

Vivian was in the yard last evening when I came home on my bicycle. She ran over and inspected it, and I told her that it was a "bicycle." As she is wont to do these days, she repeated the word quietly to herself.

This morning, as I was getting ready for work, I told Vivian that I was going to work on my bicycle. I picked up my pannier, leaned over her, said "bye-bye!" and kissed her forehead. She looked up at me and said something that made both me and Vivian's mommy gasp involuntarily. It took me a second to realize what Vivian was really saying, and I thought mommy had figured it out too, because she was laughing so hard. But, as I was going out the front gate, I could see Vivian in the front window, pointing at me. Mommy opened the window and said, bewildered, "She's still saying that!"

"It's okay, she's just saying 'bicycle,'" I explained.

A look of great relief came over mommy's face as I turned and headed to work.

What did Vivian sound like she was saying that made us both gasp? I'll let you be the judge. Here's a short video where Vivian says her new word for us all: