The Ballad of Jim Jones by The Brian Jonestown Massacre.
Absolute classic, easy to sing, easy to play (even I can manage A-A-A-E) great harmonica/whistling solo and relevant lyrics.
Probably offensively purile songwriting to the Dylan-o-philes but it served me well walking along a rain-soaked Canadian forest road and needing something to sing out to warn bears of my approach...
'I walk from New York and back from LA,
I lived on the mountain and once by the bay,
I bought an apartment and I slept in the hay,
But nowhere is softer than...'
(I don't actually know what he's alluding to in the last line, plenty of obvious possibilities...).