I've seen this joke before, but it wasn't about Africa. In Russia, a similar one was told in the 90s, except it went like so:
Yeltsin visits US on an official trip; Clinton is hosting. The banquet is lavish, and after gorging himself on delicacies, Yeltsin asks Clinton where the money for all that came from. Clinton gestures him to the window, and points at river, with bridge in the distance.
"See that bridge?"
"Yep."
"We budgeted 100 million dollars for it, but our innovative construction companies managed to complete it for 50 million. The rest of it went into our reception fund".
Next year, Clinton visits Russia. The banquet is even more lavish. Clinton asks Yeltsin the same question. They walk to the window, and Yeltsin gestures at the river.
"See that bridge?"
"Um... no?..."
"But we budgeted 100 million dollars for it. So..."
Which, I guess, also tells you a lot both about how US was perceived in Russia back then (I'm sure the notion that American contractors could do the work under budget is utterly unbelievable to most Americans; yet its believability is at the heart of this joke).
