Okay, so that's just a parody, but some of the real ones look particularly daft.
AV will make Nick Clegg president:
AV kills babies:
AV kills British soldiers:
AV is responsible for cuts to the police force, even though we don't have it yet:
AV gives everyone else more votes than you:
And AV will force them to kill this puppy!:
Okay, that last one was a parody again, but it fits in with the others pretty nicely I think.
Here's some more parody posters
from David Schneider's website: