Normally seeing that The Rock is in a movie is an assurance that it will at least be somewhat charming, if nothing else. The greatest sin of this movie isn’t the shitty script, lazy jokes, or underwhelming action. No, it’s that they managed to make Dwayne Johnson boring.
System Mastery 
Flakka is actually a real drug. It’s a designer drug like bath salts and a psychostimulant. Based on your description of it looking like silica gel, they got the appearance just about right too. One of its street names is “gravel”.
Damn, we are no longer down with the drug youth of America! We can accept this gracefully and go back to complaining about the ludicrous price of a lid these days, I suppose.
When the title shot happened with the Rock carrying the surfer guy with a head wound out of the ocean, and all of a sudden Baywatch appears in big blocky letters with CGI dolphins flipping around it, I thought was in for an awesome goofy movie. Oh, how wrong I was.