In response, the child who was walking with me told me "I also will become a dog!"
Clearly the kids were not bragging about growing a tail and fur, but rather, they were excited to tell me that they were getting a dog, not becoming one.
Correct German: "Ich bekomme einen Hund" (I am getting a dog)
bekommen (verb) - to get
Bekommen sounds a lot like "become" to anyone learning English for the first time.
I always have to chuckle whenever "become" is used incorrectly. At the same time, I'm very impressed that the kids have the capacity this early on to work out those things into English so soon, even if it is slightly incorrect.