What's more frightening than the unknown? Generally, whatever the imagination fills the gaps with.
The problem with an actual sharknado is, aside from good luck finding enough of them to suck into the thing, they would die. You pull in your sharks from the sea into the air to fling around at crazy speeds and...they would not survive. Your worst hazard is that you get hit by a dead shark.
What's more frightening than the unknown? Sharks raining from the sky, of course!
Raining Men of course, or alternatively, raining Sperm Whales or Blue Whales, cause those would cause lots of damage.
Being a Marine Biology major, I knew it was absurd, especially since it was that many sharks, and that all of them were alive. The movie was a blast, because it's a cheap movie made for laughs, and it delivered that in full, especially at the end. If the second movie is as ridiculous, or even more than the first one, I know I will love it. Next up will be Whalenado, a Pokémon parody with 1000's of Wailords being flung across all the regions.
What's more frightening than the unknown?