Your eyes don't deceive you, nor is this fan art. That's Adventure Time's Finn and Jake in Futurama. This week's Futurama episode will feature a crossover...which will be interesting because Jake and Bender are voiced by the same person!
I tried watching several episodes of AT but I guess it just isn't for me. I just don't see anything funny about it, then again, I didn't really care for Cow and Chicken either and the humor seems really similar. That Gravity Falls show is pretty damned funny though.