Oxford Dictionary: "Wilcat-adj. 1:[of a strike]sudden and unoffical. 2:commercially unsound and risky.
Prehaps they workers involved should understand both meanings of the word. Unions may not always appear to act in the best interest of their members but they are the people the company deal with and their bargining power is dimished by wildcat action.
I understand the desird effect of this kind of action is to catch the company unawares and prevent it from being able to make alternative arrangements so as to minimise disruption during offical strike action.
Wildcat action, while it may have the inital desired effect, is a risky business and should be entered into with extreme caution.