Welcome to B:mrgreen:B !!
If you are looking for something like a ‘dump’ or ‘question bank’, I am afraid you won’t them on this forum.
You can have a look at the following threads:
Link 1: BusinessObjects Certification Exams
Link 2: BusinessObjects Interview Questions
Just go through SAP BO Official Product Guides, and if you have good understanding of the tool, you should be good to go.
Rajat Sapru 
(BOB member since 2008-08-28)