“May Klingons endure!”

That's one possible interpretation. Here's another: it's Clipped Klingon, short for tlhIngan maH. mataHjaj!

And yet another: a noun has elided: tlhIngan maH. taHjaj ghu'vam!

Or a more specific one: tlhIngan maH. taHjaj wo'!

Or maybe this is an example of a verb whose subject is just so well understood that it's never actually stated, like when a Klingon feels water falling from the sky and says SIS. What is the subject of SIS? Nothing specific, but we understand the sentence all the same.

Or another: it's really tlhIngan maHtaHjaj May we continue to be Klingons.

-- 
SuStel
http://trimboli.name