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.
“Hey dude why are you walking funny?”
“ Went for a jog for the first time in ages last night, now I’m Robo-coping”.