A Rabbi walks into a bar, attired in traditional Jewish garb.
The bartender takes one look at him and says:
"Sorry, you'll have to leave".
The Rabbi, obviously offended says "Why, don't you serve Jews in here?"
The bartender replies "Of course we do, but we just found out that the place is infested with ticks and fleas, the fumigators are on the way and we have to close until the harmful fumes, that will surely emanate from the fumigation process, disperse."
The Rabbi politely apologizes for making misplaced assumptions about the bartender and leaves, rather red faced, actually.