When I was kid "gobsmacked" meant that you were very, very surprised by a thing or event.

I've not been gobsmacked for a long time because I thought I had seen it all. But then I read that

"EADS, the parent company of Airbus, is to unveil plans for a “hypersonic” plane that can fly twice the speed of Concorde on biofuel made from seaweed, and takes less than 90 minutes to fly from Paris to New York. The 3,125 mph jet known as ZEHST, standing for Zero Emission Hypersonic Transportation, will transport up to 100 passengers at more than four times the speed of sound, with a cruising altitude of 20 miles above the Earth – just outside its atmosphere."

I just want to know how they are going to shovel all that slimy green stuff into the fuel tanks.

And then there are the guys who are using biofuel from "inedible plants" to fuel an executive jet and a 747 en route to the Paris Air Show.