It seems that "chunked" is in common use.

Here are a few examples culled from North Carolina newspapers in recent years of the verb "to chunk" being used instead of "to chuck" (as used by former Gov. Mike Easley and President George W. Bush):

* Food correspondent Debbie Moose, in a March 23, 2008, article about Duke mayonnaise: "And she chunked another jar of Big D into our cart."

* Charlotte Observer sports writer Ron Green Jr. writing about Padraig Harrington at the British Open on July 23, 2007: "When Harrington chunked his 229-yard third shot into the water, visions of Van de Velde danced in every head."

* Winston-Salem Journal writer Lenox Rawlings writing about football on Jan. 9, 2006: "The Carolina Panthers, striving for legendary status as the NFL's ultimate playoff road team, read that conventional scouting report and chunked it into the Hudson River yesterday."

* Durham Herald-Sun columnist Jason Hawkins discussing a fishing trip on Aug. 3, 2003: "He said, something was wrong with the cantaloupe, and he chunked his half overboard."

The word seems to be mostly used in the context of golf, but other sports writers use it a lot as well. That could be because sports writers use a more colloquial voice or possibly because more of them are Southerners.