Sexual Innuendo in scientific and industrial terminology

Over the years, I've worked in various industrial settings, and have received some scientific training. I am also very interested in railroading. From time to time in the above pursuits, I have come across terminology that makes me wonder whether its originators had their heads in the gutter. First example: Male and Female connections.
Male Connector:

Female Connector:

I think these photos are self explanatory. Fortunately or unfortunately, nothing interesting happens when a male connector is repeatedly inserted and removed from a female connector.
Next, pipe nipples. These are short lengths of pipe with male connections on each end. Often, plumbers and other workers will refer to them as just "nipples". In the wrong situation, that could be quite humorous.
Guess what splits in rocks are called? Here's a hint:

Those strange geologists.
The fine folks at General Electric Transportation Systems have been developing this gem since 1977. It's their nomenclature for freight locomotives. It consists of a letter, denoting the wheel arrangement, a number, indicating the horsepower rating, and another number, indicating the model series, possibly with another letter indicating various options. For example, a C40-8 is a 4000HP locomotive with two three axle trucks, belonging to the DASH 8 series. Drop the -8, and it would sound as if they were referring to a certain garment in a rather muddled fashion (so it's a c-cup? with a 40in band? How and why did General Electric get into lingerie anyway?).
Finally, the sex bolt. Its a rod with a threaded hole in it, with a bolt like head on one end. This term just reeks of double entendre. Somebody needs their head examined.