Bobby is one of the secret characters that can be unlocked in the Inside Out section of Disney Crossy Road! In order to unlock him, all you have to do is unlock the 'Brain Maintenance' set of characters. These characters include Fritz, Brain Worker, Dave, and Paula. Once you unlock these characters (in no particular order) you will unlock Bobby!
If you know how to unlock any other Disney Crossy Road Secret Characters, make sure to tell us in the comments below!