Also, Trivialis, meaning in Latin "Three roads" literally, actually meant "Street Corner". Trivialis also came to mean "Street Knowledge" in the same sense that we use that phrase now. So, something trivial was something common. This eventually changed to something that is so easy anybody can do it. Things would be dismissed as trivial (and thus not worth discussing). Trivia is the plural of trivial. So, it's a collection of things that have little or no point in talking about.

Testify comes from Latin for "Witness". Testicle thus means "Little Witness". Nobody seems quite sure why the Romans called them that, but they are sure they never swore on them.

The plural of octopus is octopuses. The plural of anything ending in "-us" is "-uses" because we are speaking ENGLISH not LATIN. Even if you wanted to be an ultra-pretentious douchebag, octopus has Greek roots, not Latin, so to achieve proper douchbaggary you should use the Greek plural, Octopodes.

Drains flow in a random direction depending on their angle and imperfections, regardless of hemisphere. However, all northern hemisphere toilets flush clockwise, and all southern toilets flush counter-clockwise. This is because designers mistakenly thought that the Coriolis effect would disrupt flow if it flushed the wrong way. However, they got it backwards, as Coriolis makes things move counter clockwise in the northern hemisphere.

Shamelessly stolen without attribution from the portfolio of artist Daniel Lieske.

It's "The Journey Begins" by Daniel Lieske. Can't find anything higher resolution than that.

everybody gets one