Earlier, attempting to use a plank would tell you to directly click on a player to splank.
Now, probably since the last gameplay update, the menu offers a "Eat" option making the planks edible and giving you 2 of energy per plank.
I don't think this should happen. Glitches' intestines probably can't handle this.
And even if they could, 2 of energy is very low for the effect a plank has (it has been demonstrated several times).
Look:
http://i.imgur.com/QbBzG.jpg