My favourite graph for things has to be the graph of sales predictions for Itanium over time. It goes with anything. For example:

"The Li-Fi market was projected to have a compound annual growth rate of 82% from 2013 to 2018 and to be worth over $6 billion per year by 2018. However, the market has not developed as such and Li-Fi remains with a niche market."

@lofty some Li-Fi startup came to a job fair at my faculty but they were unable to explain to me how they pull out hundreds of mbps from conventional LEDs. Apparently the Nyquist-Whittaker-Shannon-Kotelnikov theorem scares them away.
@lofty Occasionally you do get the solar power growth graph
@lofty A random number generator might make a better prediction 
@lofty The Itanic debacle will forever be funny and I'm also thankful for it being a nice fat nail in the coffin of VLIW.