Requirements vs Delivery - Guide to Programming
This one is a killer and I've received it in multiple forwards in office email, and we always have a good laugh seeing this joke.

Client: “Our next requirement, and this is something big you know, we need an elephant”
IT Team: But why don’t you adjust with a buffalo, even it is big…. and black?”

Client: No, we need an elephant only, let me explain our current process……” (client explains for an hour)
IT Team: Fine, I understand your requirement. But our system supports only a buffalo…

Client:We need only an elephant!
IT Team: Ok, let me see if I can customize it for you”

Requirements are taken as follows:
Client wants a big black four legged animal, long tail, less hair. Having trunk is mandatory. The same was documented, signed off and sent to offshore for development!

At the Offshore Development Centre,

Design/Development – Based on requirement all features are supported in base product (as buffalo), for trunk alone a separate customization is done.

Finally the customization is shown to client: