(v.) The improper act of having, or trying to have intercourse with a largewoman, typically on a weekend night. Derives from the word chunker. A large woman can be referred to as a chunker.
"Yo bro, lets finish this beer and go out to this party. If I get really drunk tonight I might go chunking"
Chunking is the act of shitting for your friend/patient/random tramp by fisting said person in the rectum and pulling the shit out of them. The act may be considered one of generousity but it is sometimes necessay to go that extra mile for a friend.