The average rate at which Americans tip for services has been increasing steadily for decades, which creates a growing pay disparity between tipped and nontipped workers. The practice has been branded over the years as classist, anti-egalitarian, and downright undemocratic, leading some restaurateurs to abandon it. A new paper, drawing insight from nonlinear dynamics, hopes to shed light on the economically irrational world of tipping, showing that at a certain point, banning the practice might be fair and profitable.