“Men in Black 3” is a paycheck movie for everyone involved, except the audience, who again get another middling, phoned-in sequel looking to drain their wallets with its average 3-D-ness.

Will Smith and Tommy Lee Jones again return as agents J and K, except Jones much more briefly. His Agent K has been extinguished, all part of a plan by alien baddie Boris the Animal (the always-funny Jemaine Clement, “Flight of the Conchords”) to go back in time and exact revenge on the agent for imprisoning him and destroying his alien race back 40 years ago.

Some temporal fracture allows J to still remember he had a partner named K and so he must go back to 1969 himself in order to make sure both future and past Boris’ are dead and K (played by Josh Brolin in the past) is alive or it will mean a huge alien invasion in the present.

Emma Thompson is also on hand as Agent O, taking over as leader of the Men in Black (I wondered how well women fair in this organization) from Rip Torn, while Michael Stuhlbarg (“Boardwalk Empire”) gets an annoying role as a psychic motor-mouth who also holds key in making sure this ends happily.

The script for this was supposedly still being finished when director Barry Sonnenfeld started filming and it shows. The time-travel stuff is flimsy, J’s temporal fracture is never really explained, but it wouldn’t be nearly as evident if “MIB3” did what it was supposed to do in the comedy department.

I laughed twice, once at an Andy Warhol joke and the other at the neuralyzer of the sixties.

Part of the fun of the first film was the eccentricity of these alien beings, but now that has worn thin. The surprise is gone and even slapsticky moments like throwing an alien head down a bowling alley runway never take on the desired effect.

The CGI and make-up creation on the aliens still look goofily cartoonish, but this time it’s for the benefit of just looking like expensive special effects than being cleverly funny. The same goes for Boris, probably the dullest of all the series villains.

He looks like a Hell’s Angel who can shoot spikes—nothing special.

Smith is given terribly lame lines (stuff about using cell phones on airplanes and flushing fish down the toilet) that he fast-talks with the same cockiness that gets so grating when he really doesn’t have any material to say. Jones just seems disengaged from the whole thing, and Brolin does an excellent Jones impression but he also did a good George W. Bush impression too and he couldn’t save that movie either.

I assumed this journey into the past was going to allow us some insight into K but the Brolin character, and the chemistry he has with Smith, never yields much of anything until the ending, which leads only to more questions.

Some will say “MIB3” is better than the second one, but who cares? It’s a far cry from the first one. You’ll hardly need a neuralyzer to forget this hopefully last installment of the series.