If you can program [1], you can do BFS - no need to "invent" anything. Given a tree like this [2], asking you to "print the numbers in order" is not a difficult question, it's a trivial one.
I would expect any interviewee that calls themselves a programmer to talk me through a reasonable answer to that question. Forget about what BFS means - you don't even need to know what a tree is. Looking at the image is all you need.
