It is not a hang-over from the days of flower power. The word actually comes rather indirectly from "BUM" meaning tail end and was first applied to stragglers and hangers on who attached themselves to General Shermans march from Atlanta to the sea during the American civil war, Thus the word bum means a sponger or a tramp and through a somewhat circuitous route ultimately has its root in the English word "bum" meaning rear end.
Surely this is the beginning or the end of an essay or ode to that wondrous feature of the human form. I thought this was a different way of thinking of the posterior where indeed so much of our pain radiates from.
So we begin with the end and lets see where it takes us, what journey will it
tr.avel to make us smile