What if there was an election and Anonymous showed up?

I'm sure 4channers already do vote. They're diluted enough that they don't make any difference.

Part of the power of Anonymous is that they are geographically distributed -- i.e. not part of the same voting districts. In something like a national race (like POTUS, for example), they wouldn't have enough members to significantly affect the results.

The DHS would get a whiff of it and they would arrest them and put them in one of those fancy prison institutions that strangely have nobody working there [yet].

They would yell lines that nobody understood, everyone would be thoroughly confused and news outlets would do stories on them that miss the point (or lack thereof) entirely.