Sharing the excitement of big data, while steering the conversation toward corporate data, lets the CIO temper some of the enthusiasm with realism.

First, define "big data"
Half the challenge of discussing big data is that there is no single product or tool that represents it. Unlike an iPhone or ERP package, big data is more a concept than a product or clearly defined set of criteria. When speaking with a peer outside IT, try to determine precisely what they're referring to when they broach the subject of big data. Are they referring simply to rapidly analyzing large volumes of existing corporate data, or trying to process massive sets of unstructured data? Do they want to incorporate external or environmental data into existing reporting to provide more insight, or do they want to throw massive data sets at PhD-level data scientists to see what comes out?
More often than not, when people start referring to "big data" they're more interested in incorporating existing enterprise data and rapidly performing ad-hoc queries across applications than wrangling massive sets of unstructured data and performing exceptional complex analyses. Taking the time to define "big data," and realizing that Marketing may have a very different definition than Accounting will ease the discussion.
Forget the "big" and focus on the data
In many organizations, data are siloed in various departments and applications. Even a single business unit might not be able to produce a seemingly straightforward report, since the data required are not linked or consolidated. Much of the attraction of big data to those outside IT is the assumption that this new technology performs some kind of technical magic, allowing any and all data sources within a company's four walls to be quickly linked and analyzed.
These scattered data sources often indicate a company is not yet "data mature" enough for true big data and could likely benefit from some more basic initiatives like building an enterprise data warehouse, building a basic Business Intelligence capability, or deploying a user-friendly reporting and analysis tool.
Is "big data" code for "better reporting"?
Bottom line
The good news about all of the hubbub around big data is that it creates an opportunity to talk about, and get funding for, data-related initiatives. Sharing the excitement around big data while steering the conversation toward corporate data in general lets the CIO temper some of the enthusiasm with realism, and often retarget a big data initiative toward something more realistic and beneficial in the near term. Even if you're not technically correct in referring to a basic data cleansing and consolidation exercise as "big data," the growing interest around the subject just might let you build some increased capabilities that accelerate your "data maturity" far more than an ill-conceived and unwarranted initiative.