Return to the Nightosphere
Finn and Jake wake up in the Nightosphere in a jail cell filled with bananas. They have no recollection as to how they got there. They learn from a video on Jake's phone that they stepped through a portal the night before but then Jake's phone runs out of juice.
Finn and Jake spend the rest of the episode looking for Hunson Abadeer, Marceline's father. They find him and fight with him. The fight ends with them discovering that he is Marceline in disguise.
Thoughts
It looks like Jake and Finn return to the Nightosphere in the next episode.
This was fun, gross, and weird. I liked it.