The women of a history class were starting to get tired of the offensive jokes their professor would tell at the beginning of class. So they came up with a plan, when he started to tell a joke they would all get up and walk out.
The professor heard of this plan and went to class the next day and started to tell a joke.
"Class, did you all hear about the shortage of whores in India?" he started with.
The women of the class all got up and started to leave.
To that he replied "Ladies!! Don't rush off, the boat doesn't leave until tomorrow!"