I found this most excellent
site which describes a number of (presumably) real-world stories, wherein salepeople
of various stripes encounter any number of humorous (and often self-inflicted) obstacles.
Here is a little taste:
“We drive back to the prospect's building and sit in the visitor's
spot, mentally preparing and drinking frozen pop.
When we're ready to go I look over and his mouth, lips and tongue are
BRIGHT GREEN - I mean really bright, like a clown.
Mine, of course were GLOWING RED”