The episode ends on a classic HIMYM note of ambiguity. Future Ted admits that even he doesn't know what really happened. Marshall eventually tells so many conflicting versions—including one where he fought off a —that the true events of that night remain a mystery.
Marshall realizes that if he sticks to the monkey story, the zoo might have to euthanize the animal. If he tells the truth, Lily will be terrified of the city. The Resolution [S5E19] Zoo or False
Barney, sensing a great story, tries to get Marshall on a local news segment. The episode ends on a classic HIMYM note of ambiguity
As the episode progresses, the story spirals out of control: sensing a great story