I was in a hotel kinda thing where I went to a waterpark with a bunch of different pools and even weird spinning water bucket machines. At one point I decided to go to the (smaller than normal) lazy river and Finn and Jake came over and decided to have a race where we see who swims around it the fastest. I went first, then Finn went, but when it was Jake's turn, he turned the lazy river into some sort of pho-like soup for some reason. I don't think we ever determined a winner, but I'm pretty sure it was Finn.
The other part of the dream was me finding my online friend's dad (who was NOT their dad by the way) and getting into a weird mini-car (not like a toy car, but not like a normal car either) with him and someone else. We went onto the road and he started being a jerk to other cars by yelling insults at them "for fun". At one point he even threw something at one. When we got to the back of the hotel, I was wondering where Finn and Jake were, but my friend's dad said he didn't care and wanted to ride the car again.
It was really strange, but honestly the first part of this dream was better than real life :(
Edit: Oh yeah, almost forgot to mention that I don't even know that much about Adventure Time. I know a few random lore points, but I don't watch enough of the show to know the full thing.