What is the origin of expression how's Trix?

Answer 1

it is uncertain

sailors are often credited as the source since they have long called their shifts of duty tricks

but cardplayers & especially hos & pimps have also been suggested

as the expression appears to be 20th century American English

I never heard any of my shipmates call a "shift of duty" anything but a "watch." My Great GrandPappy Zebadiah Chandler always told me that "Trix" was a Latin suffix used to form feminine nouns and adjectives. He added that it was often used in the English language for the same purpose (i.e., executrix, dominatrix). American slang uses the suffix to denote an attractive single female (trixie) or to refer to the wife of a close friend (How's Trix?).

Answer 2

The expression "How's tricks?" originated in the early 20th century as a slang way of asking how things are going or what's new. It is similar to asking how someone is doing or what they've been up to. The addition of "tricks" likely comes from the idea of someone showing off or performing tricks like a magician.