Katy (friend of Bill and Tom) put photo of her dog's with Bill coat.

Katy, girl friend of Kaulitz, posted a picture of her dog in a jacket that appears to be the Bill, used in that photo above. She is in New York. It may be that the twins were with her and Alex, who is also their friend. The fact is confirmed by the fact that most of the Bill have posted a picture of New York a few days ago in BTKAPP.

source

*I'm using translator