Voting with pencils and the "nothing to stop your vote being altered using an eraser" conspiracy theory.

Why pencils?

1. You can leave them in a box for a year and it won't dry out.

2. When you fold the ballot, wet ink can transfer and make a second "x" (invalidating your vote).

To change your vote, someone would need to open the ballot box, which is why candidates are allowed to add seals to the box and inspect them before counting.