It's possible that:
* It's a typo: Perhaps the intended word was "anniversary."
* It's a foreign phrase: It could be a phrase in another language, with a different meaning than the intended one.
* It's a creative invention: Someone might have invented the phrase for a specific purpose, such as a fictional story or a unique brand name.
Without further context, it's impossible to determine the exact meaning of "Zwaye Zaniversair."