It doesn't actually really work because if you later view your comment it doesn't reflect your extra vote. But it is possible to make the app give you the impression that you just earned an unearned imaginary internet point lol.

If you downvote your own comment and then upvote it again, it doesn't return the net balance of this action, instead double counts your upvote. If you had 1 point like you do by default when making any comment, and then downvote that, it goes to 0 points and then if you upvote, it jumps to 2.

Discovered by accident when accidentally hitting the downvote button and trying to correct it. Guess it's not really important since it didn't appear to actually really manipulate the vote count just temporarily display it wrong for the specific app user but still.