Buckling seatbelts: Absolutely no "male-to-female" connections.
When I worked in IT at a community college I had to explain to a little old lady there, and when I say little old lady I mean she was the epitome of a little old lady, which end of a cable was male and which end was female. When she was still somewhat confused I had to make how to tell which end is which a little bit more graphic. When it finally clicked in her head which one was called male and the other female and why she turned solid red.
