|Out Of the Box Siebel|
This is how i explained him. Siebel is a packaged CRM application sold by Oracle for various industries.
Package application means that application is pre-built to support best business practices. There are some basic functionalities which already exist in application(like contacts, accounts and activities etc.... For specific industries it may have orders, quotes, cases , incidents etc..)
Thus when first time Siebel CRM is installed on server, the application you get is known as Out of the box Siebel application. Literally like straight out if the box.
You might have heard from Siebel consultants saying that email processing is available out of the box in Siebel, that means oracle has already developed support for email processing and there is no need for development.
Development is required only when some different functionality is required than "OUT OF THE BOX" Siebel or sometime referred as OOB. This development is known as customization.
Hope this might help you in answering your PMs.