'Family Guy' meets 'The Simpsons' in crossover clip

What happens when two of animation's ruling families meet? Donuts are had, beer is shared ... and things quickly go awry.

At San Diego Comic-Con over the weekend, Fox released a nearly five-minute clip of their anticipated "Simpsons" crossover episode featuring the Griffins from "Family Guy."

In the teaser, the Griffin family finds itself in Springfield, a seemingly nice town that leaves Peter Griffin suspicious of the water since everyone "looks like they have hepatitis."

Before long, Homer Simpson and Peter Griffin are buds, as Bart teaches Stewie his best prank-calling and skateboarding tricks.

[youtube https://www.youtube.com/watch?v=-7YzXMzZ1bU?feature=player_embedded&w=450&h=360%5D

But before the Griffins decide to make Springfield their new home - even if they're not allowed to say what state it's in - Peter and Homer's budding friendship dissolves into a massive, intergalactic fight.

The "Family Guy"/"Simpsons" crossover episode airs with "The Simpsons" fall premiere on September 28.