What is the best way to prune a "wandering jew" plant?

Is this some sort of anti jewish joke?

No, definitely not – there is a houseplant that is commonly known as a “wandering jew” plant. I’m Jewish and am definitely not trying to make an anti-semitic joke. It’s a common houseplant and looks like this

Pinch off the jewlets (ljust below where they attach to the mother) with your thumb and index finger; then repot them. But beware, they can take over your life, like Audrey II.

You can also hack in any way that you see fit. The plant is indestructible.

Wandering Jew, member of the large tradescantia family, including spider plants, many more. I’ve never bothered to look into the etymology, how it got its moniker; but I suppose it’s because it grows so viney, spindly, “wanders,” etc. Not sure what climate you’re in, that’s important. I agree with @gailcalled answer; very hearty, they also make nice hanging baskets, for a change of pace from green—their unique maroon coloration; they even have nice little white blossoms. One other tip: You can cut off a few inches of it, put a handful of the cuttings in a water glass, whatever container, with water, and they root fairly quickly. Give them time to show the new roots, then stick ‘em in the soil with the original one for added density, fullness, or start a new patch, pot, basket.

Wikipedia says “The colloquialism “Wandering Jew” is of indeterminate provenance insofar as being applied to the plant in question; it cannot really be said when, where, or by whom it was first called this, but, considering the term’s negative connotation, it would perhaps be safe to assume that the originator’s intent was not to highlight the plant’s more favourable qualities.” And then there’s this.
Dictionary.com says pretty much the same.
I’m pretty sure the purple one was not considered a Tradescantia when I was young… those crazy botanists!
And while not completely indestructible (read: forgetting to water drought), they sure are tough little buggers.

Pinch him good! he will respond with more branches.

Edit—Self control won over!

Circumsize it!

@janbb tsk tsk, no self control

You got that right, boyo!