Via Wilson Gray on Facebook, this New Yorker cartoon by David Sipress:
So: the idiom play dead, plus the band the Grateful Dead.
From Wikipedia, on “Casey Jones”:
“Casey Jones” is a song by the American rock band the Grateful Dead. The music was written by Jerry Garcia, and the lyrics are by Robert Hunter. The song first appeared on the Dead’s 1970 album Workingman’s Dead. Subsequently it was included on a number of their live albums.
Driving that train, high on cocaine,
Casey Jones, you better watch your speed.
Trouble ahead, trouble behind,
And you know that notion just crossed my mind.
The studio version:
As a bonus, another linguistically relevant Sipress cartoon:
… on the No Split Infinitives silliness (most recently on this blog, here).