skate rocks

this means fuck off ( F-off ) plain and simple

this originates from skateboarding world,
it is similar in origin to suck lemons,
you can 'suck lemons' or go suck lemons or you should suck lemons
are all replacable with F-you or F-off or skate rocks
meaning, skateboarding in rocks or gravel is NOT fun,
so,, you can skate rocks, would be a usage from its origin, but now, it is like most F-off/F-you phrases and can stand alone, and not be so grammatically correct
such as, 'people that are cruel, skate rocks and leave me alone;

If you dont like what I say then skate rocks.