Alternatively: "I'm voting for Diet Fascism and if you don't vote for Diet Fascism too, you're voting for Full-Fat Fascism" but said with the sternest voice the weakest losers can muster.
More "I'm voting for diet fascism and if you don't vote you're complicit in anything that comes, which will either be diet fascism or full-fast fascism. Not voting doesn't prevent either of these, and one is obviously preferably. No action is still a choice you're making."