He dried out a Granny Smith apple and Sunkist Navel orange in an oven, ground them up and put each into a mass spectrometer. In fact, he found apples and oranges are pretty similar.
"Not only was this comparison easy to make, but it is apparent
from the figure that apples and oranges are very similar, This
it would appear that the comparing apples and oranges
defense should no longer be considered valid. This is a
somewhat startling revelation. It can be anticipated to have
a dramatic effect on the strategies used in arguments and
discussions in the future."
-as excerpted from here
enlargeable cartoon here