Yup. It was.

I'm not sure that it was racist, yes, it noted stereotypes,
had the usual manic sexual references etc.

Typically the descendants of slaves, that have been fortunate
enough to enjoy an adequate diet are through evolutionary
pressures physically fitter.  The black man in the story
demonstrated humour and perception, the suggestion that he was well
endowed may have been a mere statement of fact of which
he was both pleased with and lacked the self effacing hypocricy
of false modesty.

Again stereotypically the white individual responded with fear.

Were these stereotypes extrapolated into a generalisation
then the joke would have been racist.  However reference to
a stereotype does not of necessity indicate bigotry as there
tends to be a statistical skew amongst different populations
to have led to the creation of the stereotype in the first place.

If one views this joke in the context that there are different
groups of people with different characteristics yet these
differences do not indicate superiority/inferiority in any
absolute terms, then the joke merely acknowledges an aspect of
reality.

Until we acknowledge the existence of difference and appreciate
it as part of the richness of life, and respect each individual
and group for their respective talents, then there will always be
bigotry.

Current trends in political correctness and refusal to appreciate
that different peoples have a predominance of different characteristics
and talents, yet both we and them have absolute value as living beings
that need to recognise and respect differences.

Jokes, usually challenge preconceived views on reality, and that
includes political correctness.

Unless there is frank dialogue on race and culture within and between
groups, then there will be no understanding or respect, and false
opinions and beliefs will fester behind closed doors.

Describing the joke as "racist" is mere prudery.  The differences
were sensitive, but I felt there was no particular judgemental-ism.

As for the stereotype that blacks have "better" sexual prowess,
we just have to accept that this holds true
for statistically significant proportion of that population.

Another individuals sex life is none of my business unless they
make it so (or I do).  However, I have vicarious pleasure, and
admiration of the athletic ability of others, and recognise
that though I may envy this or that property in another that
there are swings and roundabouts in life, and that we can all
find value and happiness, or at least work toward it in life.