"Mr. Tux" is the ninth episode of Season 2 from The Penguins of Madagascar.
An armadillo who goes by "the Amarillo Kid" enters the penguins' habitat looking for someone he knows simply as "Mr. Tux." Private admits to being him, and the Amarillo Kid insists that Private engage in some sort of "unfinished business" with him, but Private refuses.
Soon, the nature of Private and the Amarillo Kid's past is revealed: Private was once a skilled mini golf player, but quit the sport after a tough game against the Amarillo Kid forced him to have to ricochet a ball off of a young possum girl's ice cream cone, destroying it. The other penguins and Marlene find it ridiculous that he would just quit after spoiling a double-scoop of ice cream when he could've just made it up to the possum by buying another. Nonetheless, they decide to stick behind him.
Private decides to take on the Amarillo Kid in another round of mini golf only after the armadillo sets the penguins' HQ to self destruct and locks-down the rest of the zoo. When Private's game-wining putt comes a mere fraction of an inch from going into the hole, the Amarillo Kid celebrates his long-awaited defeat of Mr. Tux.
But Private's ball then rolls in, giving him the victory, with an assist by a cricket that Private had avoided hitting earlier while driving the penguins' car.