The first thing that I imagined when reading the subject of this thread was people feeling pissed off at being forced to vote. Then voting for some populist 'fuck you' candidate just out of spite. I might be overestimating the nation's potential for engagement, perhaps it would just be donkey voting like
Gerry1time says.
I was forced to vote by my father when I turned of age because it was my 'civic duty'. Needless to say, I threatened to vote for a party I was sure he'd hate and then eventually I just destroyed the ballot by drawing a bunch of bollocks and writing 'this election sucks' on it. I'm older and more mature now but it doesn't mean other people are.