http://www.jargon.8hz.com/jargon_35.html - see thunk, and meaning 3 is what I've been using.
jargon.org is the official site, and it has a more detailed definition:
http://www.catb.org/~esr/jargon/html/T/thunk.html
Beware of definition 4, which can cause confusion in the Windows environment. It's the one I thought was being referred to when I first saw this subject line.
