A peaknik is a peak oil enthusiast and activist.
My damn peaknik roommate is always yammering on about doomsday and victory gardens!
A peaknik is someone who believes in the theory of Peak Oil, namely that the maximum rate of production of oil fuels may be reached soon or has already been reached. Peakniks often are obsessed with this issue because the difficulty of replacing liquid fuels could bring crisis to modern, industrialised economies.
"These aren't the claims of a rabid peaknik, they are predictions made by investment bankers and oil industry analysts."