He can point out the male paradise whydah with its unusually long black tail feathers.

VOA: special.2009.08.19

As gold aversion surged, investors bought gold to hedge out tail risk and destructive scenarios, including a Cypriot Eurozone exit and political risk in Italy, where Pier Luigi Bersani has failed to garner support from Silvio Berlusconi and Beppe Grillo of the 5-Star Movement to form a government.

FORBES: Central Banks Bought More Than $3B In Gold In 2013: UBS

Run a car on hydrogen and pure water drips out the tail pipe.

FORBES: Breakthrough in Biofuels? Maybe.

The car doesn't need the carbon dioxide to run, so it sends it out the tail pipe and into the atmosphere.

NPR: Has the Move to Make Cars Greener Stalled?