They say "the road to Hell is paved with good intentions". Well, there is nothing truer than that when you look at those stupid valves inside modern gas can spouts. 
Not sure how a gas can is any safer with stupid valves in the spouts to try to "idiot proof" pouring gas, but they work very poorly and are a PAIN IN THE ASS and make pouring gas a tedious, long drawn out process!!!
We've had a gas can for a few years now that has been a PITA. Last year, I bought a 5 gallon can at Walmart to carry spare diesel. I just got around to dumping it in a vehicle, and this newer gas can is EVEN MORE of a PITA than the old one!!!

I ended up having to force said valve down, and clamping the nozzle with vice grips to hold valve open!!!
It simply would not work as it was "supposed to" in my car's fuel filler, and even with my mod, it still took excruciatingly LONG to empty can. 
I had hoped to replace older can with emptied newer on, but I apparently need to redesign nozzle, and RIP valve out completely!!!
Not sure how a gas can is any safer with stupid valves in the spouts to try to "idiot proof" pouring gas, but they work very poorly and are a PAIN IN THE ASS and make pouring gas a tedious, long drawn out process!!!
We've had a gas can for a few years now that has been a PITA. Last year, I bought a 5 gallon can at Walmart to carry spare diesel. I just got around to dumping it in a vehicle, and this newer gas can is EVEN MORE of a PITA than the old one!!!
I had hoped to replace older can with emptied newer on, but I apparently need to redesign nozzle, and RIP valve out completely!!!