The mug belonged to Princess Bubblegum. That means she likely lived with Marceline at some point after they kissed (!) during the Adventure Time finale.

Cartoon Network has given series renewals to Adventure Time, Regular Show, Uncle Grandpa, Steven Universe and Clarence. Emmy-winning Adventure Time and Regular Show have been re-upped for a ...

Cartoon Network has renewed five of its original series, “Adventure Time,” “Regular Show,” “Uncle Grandpa,” “Steven Universe” and “Clarence,” the Time Warner-owned cable ...

‘Adventure Time,’ ‘Regular Show,’ 3 More Renewed at Cartoon Network (Exclusive) 'Uncle Grandpa,' 'Steven Universe' and 'Clarence' will also return for additional seasons.

Speaking of which, how did you get “Adventure Time” creator Pendleton Ward to animate the opening credits for “Uncle Kent 2”? Pen is kinda moody and has his own stuff he’s working on.