When I was teaching, I picked up this silly little book, Maisy Drives, at a used book sale. I was buying any board book I could find to put in the library of my classroom. My students had a knack for destroying books.
The book consists of pictures of Maisy, a poorly drawn white mouse, driving different types of transportation. The book tells the sound the vehicle makes. The train says "choo, choo", the tractor says, "chug, chug" and, apparently, the tricycle says "rattle, squeak, rattle, squeak".
For this reason, whenever Isla rides her tricycle around our house, which she spends a good portion of her day doing, she likes to say "rattle, squeak, rattle, squeak". Only, Isla struggles terribly with her diction, and what she actually says is "abba key, abba key".
So, if you stop by our house, and my little one rides by saying "abba key", don't be concerned. Just blame Maisy.