Nitrogen fireworks in Waterloo.
This is how I would label PI's last public lecture of the 2007-2008 season "Time and Einstein in the 21st Century: The coolest stuff in the universe".
It happened at the beginning of last month but its reverberations will be felt for long time.
Here are some "keywords" that would characterize the lecture: time, atomic clocks, balloons, "really, really cold stuff", slow atoms, excitement, explosions, nitrogen "fireworks" (balloons exploding), "lots of really really cold stuff flowing on the floor", incredible clocks precision.
William D. Phillips, a Nobel Prize laureate, proved that science lectures could be really, really, really entertaining.