A scene from the original Sharknado.

A scene from the original Sharknado.

Ok, so nobody actually needs to know anything about Sharknado.

All you need - and probably want - to know is right there in the title: yes, that’s shark and tornado in one word.

The ultimate fish-out-of-water B-movie, Sharknado is a low-budget, deliberately dreadful, schlock-horror TV film about airborne sharks that would have swirled into pop-culture oblivion like so many other crappy monster movies if not for a curious explosion of social media interest on the night in July that it screened on the US SyFy channel.

The fast-moving Twitter storm sparked by the film became such an international talking point that Sharknado was rushed to air on Foxtel in Australia and - bizarrely - picked up for a big-screen showing in selected Hoyts cinemas in NSW, Victoria, Queensland, Western Australia and the ACT.

Variously hailed and howled down as the "best worst movie ever" and making "Snakes on a Plane look like Citizen Kane", Sharknado screens at Hoyts Woden on Friday night as a one-off for Friday the 13th.

Like all truly awful movies, Sharknado is an experience best shared - otherwise, what is the point of a movie about tornadoes that sucks and blows?

Here, then, are 10 things you probably didn't want to know about Sharknado:

1. The plot: A tornado* off the coast of Los Angeles sucks a school of man-eating sharks out of the Pacific Ocean and hurls them at Tara Reid. So far, so good. *See point 6 below.

2. The cast:  Joining American Pie has-been Reid to fight the hungry hailstorm with terrible acting are fellow Hollywood B-listers Ian Ziering (aka Steve Sanders in the original Beverly Hills 90210), Aussie Jaason Simmons (one-time Baywatch star) and John Heard (aka Macaulay Culkin's Dad in Home Alone).

3. The special effects: They aren't one bit special. They are plain embarrassing. Indeed, the sharks, waves and tornados are so totally lame, your groans drown out the splatter and the screams - and even the roar of the chainsaw.

4. The chainsaw: Yes, Ziering uses a chainsaw to parry and fillet the flying sharks. As you do.

5. The continuity: Logical sequencing of scenes and frames is simply non-existent in a 98-minute film made for a $1 million in 18 days and clearly pieced together from leftover bits of old TV newscasts, TV shows and stock aerial footage all tarted up with dodgy-looking digital dorsal fins.

6. The science: You don’t need a science degree to know that Sharknado plays a trifle loose with the meteorological facts. The laws of science - or narrative - are not allowed to get in the way of a hungry hammerhead hurtling down Hollywood Boulevard.

* Tornados form over land and hurricanes form over oceans, so Sharknado should technically have been called Sharkicane. In case you were wondering.

7. The social network: We only heard about Sharknado because everyone started talking about how much it was being, you know, talked about. The hashtag #Sharknado sent Twitter into a 5000-tweet-a-minute frenzy during the film's  US TV premiere on July 11.  Its 350,000 Tweets came within a few thousand of matching the Twitter meltdown caused by the Red Wedding episode of Game of Thrones. 

8. The Tweets: Hollywood writer/producer Damon Lindelof (@Damon Lindelof) – the man behind TV series Lost and the JJ Abrams reboot of the Star Trek franchise – was a key contributor to the #Sharknado frenzy, tweeting:

And later:

Actor Wil Wheaton - who is not actually in the movie, by the way -also led the charge, and he has 2.4million Twitter followers.

Acclaimed film and theatre actress Mia Farrow seemed lost for word:

Star, writer and producer of US TV’s The Office B.J. Novak:

Even the Red Cross in tornado-hit Oklahoma joined the fun:

Bizarrely, Sharknado was the last thing Glee star Cory Monteith tweeted about. On July 12, Monteith, who was to die two days later, tweeted:

9. The Aussie jokes: When Simmons, playing the obligatory larrikin Aussie, survives a shark attack, someone quips: ‘‘Sharks don’t like Vegemite". Later on there's a reference to him having "a kangaroo loose in the top paddock". Yes, their schtick stinks.

10. The title. Inexplicably, Sharknado was originally going to be called Dark Skies. Huh? Thankfully, the producers came to their senses and recognised the pure, Snakes on a Plane-like genius of giving Sharknado a does-what-it-say-on-the-lid title. It certainly worked for SyFy channel's earlier masterpieces Sharktopus (2010) and Piranhaconda (2011).

10 WORST SHARKSPLOITATION MOVIES TO DIE FOR (OR AVOID)

Jaws: The Revenge (1987): This time *cough* it's personal. The forgettable fourth and final Jaws movie.

Sharks in Venice (2008): You’re gonna need a bigger gondola! Stars Stephen Baldwin. Of course.

Malibu Shark Attack (2009): A tsunami unleashes prehistoric goblin sharks.

Shark Swarm (2008): Ex-mermaid Daryl Hannah (from Splash) and ex Bo Duke John Schneider (from TV’s Dukes of Hazzard) battle toxic sludge-fuelled sharks.

Sand Sharks (2011): ‘‘Just when you thought you were safe out of the water’’. 

Two-Headed Shark Attack (2012): The hook-line's a stinker: ‘‘1 body, 2 heads, 6000 teeth’’. But it does have Carmen Electra in a bikini.

Mega Shark Versus Crocosaurus (2010): Stars Jaleel White (aka Urkel from ’80s sitcom Family Matters). Oh, the horror!

Dinoshark (2010): Global warming thaws a prehistoric beastie trapped in ice.

The Reef (2011): Great Barrier Reef + great white shark = great big flop.

Bait: 3D (2012): Sharks stalk shoppers trapped in a tsunami-flooded supermarket. Clean-up on aisle 9!

10 BEST SHARK MOVIES EVER*

Jaws (1975): The first and only great movie about great white sharks. Or any sharks, for that matter.

Propelled by composer John Williams' foreboding attack theme, Steven Spielberg's thrilling creature feature set the standard for the modern Hollywood blockbuster.

Almost 40 years later there has not been another shark movie to match Jaws. Spielberg's eight metre mechanical shark (nicknamed Bruce) caused the director and his film crew endless grief but it was worth it for the enduring horror of Robert Shaw's climactic final scene, as his salty fishing boat skipper is dragged cursing into the deep by the monster with the dead eyes.

*We're gonna need a shorter list.