The act of walking awkwardly with stiffness in your legs akin to that of iconic 80’s character Robo-Cop.
This usually happens the day after exercising after having not done so in a while.
Other causes may include not stretching properly, or sitting down in an odd position for a long period of time.
As seen on many porn sights, a form of porn popular in japan that involves japanese men slapping or punching japanese girls' titties repeatedly, very hard.
Guy 1: Hey, why is he slapping her boobs?
Guy 2: Some weird type of porn called caning...