A phantom
A phantom is a piece of crap that shows up outta nowhere, like magic, and you swear it was your buddy who dropped it but you got no proof.
Rodney wakes up to a giant turd outside his tent and blames Jerry, even though Jerry was still asleep.
Sam walks into his neighbor's yard and poops right by the letterbox because he's had enough of the daily mess.
At the park, Lena finds a phantom on the bench and immediately thinks her mom did it, even though her mom was at work.