It's Always Sunny in Philadelphia (2005)

S4E7 Who Pooped the Bed?

Title: Who Left the Surprise? Plot: Charlie and Frank are startled to discover a mess in their bed. With neither willing to admit responsibility, they enlist Mac and Dennis to help them figure out who the culprit is through a series of experiments. Meanwhile, Dee opts for a more refined approach and organizes a girls' night out with the waitress and Artemis, hoping to unwind away from the chaos.