An idiom which states an increasing amount of danger or tension, similar to "
the shit's hitting the
fan" only much more terrible and apocalyptic. The phrase is partly
ironic, as if to exaggerate the rather mild (though hilarious) premise of the "Snakes on a Plane" movie starring Samuel L Jackson, which has snakes on a plane.
"How bad was the motorway
pile-up?" "Let me tell you, it was like snakes on a
plane down there."
"How's your relationship with Chloe going?" "It's getting close to being like snakes on a
plane man, seriously." "Damn, dude."