Everyone from your clan puts their fingers in the ground as a way to resist their lords. Your clan is made of a bunch of peasants, but you aren't going to work the land for other people anymore. You're going to resist. This is a protest! Your fingers work for no one but yourselves from now on!
You're all resisting with your fingers in the ground, when the lords appear, angry. "You resist us by hiding your fingers with potatoes in the ground?! You want your fingers to be useless potatoes so badly? We'll chop them up and turn them into tater (てい) tots!"