v. To access the data on a wireless network without authorization.
Other Forms
Whacking Into a Wireless Computer Network

Most company computer networks are protected by a firewall. The firewall allows authorized users within the company to access the computer network. It also keeps out unauthorized users. But a wireless hacker — or whacker — can identify an unprotected wireless access point inside the company's firewall, he can easily access it. Using free tools readily available on the internet, whackers could also crack through many protected access points.
—Howard Wolinsky, “Experts tell how to keep 'whackers' out,” Chicago Sun-Times, July 21, 2002
2001 (earliest)
Companies have been concerned for years that they might get hacked. Now, they're also worried about getting whacked.

Whacking is wireless hacking, usually done by a person who's in the right place at the right time with the right kind of radio transceiver. By whacking, an intruder can tap into private communications going across almost any wireless network.
—Matthew G. Nelson, “Wireless Goal: Don't Get Whacked,” InformationWeek, July 09, 2001