Here's one to begin with about work humor:
"Boss, how do you reckon us being able to work twice as hard as now, we already work overtime?"
"Well, you know what, I might have to answer your question there with another question. What are the chances of a rhinoceros and a man mating? Anyone? Zero when the mood is wrong, and very high when the music is just right. I should know, just look at my son sitting there in his glass cubicle all important looking picking his nose. That dumb-witted nose ring-sporting wild boar is certainly not purely bred out of my loins, I tell you that.