"The Fansworth Parabox"
So this was an interesting episode which dealt with Parallel Universes and their many different outcomes in terms of simply flipping a coin. Filled with good quotes and memorable moments, The Farnsworth Parabox is one of the best episoes of Season 4/5 as a result.
The episode begins with Farnsworth doing an experiment whilst Fry keeps trying to ask Leela out. Leela's excuses for not wanting to don't work on Fry, and in the end Farnsworth finishes the experiment.
The professor tells the crew about the object he used for his experiment, which is a Parallel Universe box (though he only tells the crew about the box and not what's inside). He tells no one to look inside, and in the end he lets Leela guard it from the others. Leela successfully fools the others from taking the box by switching it, in which Fry and Bender fall for it.
Leela gets through the whole day without anyone peeking the box, and gets annoyed on not being able to have even a slight peek on what's inside. Whilst heading for a coffee vending machine, Leela gets a coin out and decides to flip it whether to look inside it or not, she gets Heads so she decides to look in, only to be sucked into the box.
Leela comes out of the other side, and realises she's in a different universe, noticing the many changes in the crew and the environment. The 2nd Leela forces the crew from the original Universe into the new one, and as a result they are assumed to be the evil crew.
Both crew Universes discuss on what has just happened, and conclude that both boxes have Parallel Universes. The 2nd Farnsworth has hidden the box for the time being, and when convinced that their parralel selves are not evil, they will let them go back as a result. The original Leela also finds out that their Parallel Fry and Leela selves are also married together as well.
With having to live in the Parallel universe for a while, the crew try to get along with each other. Bender meets his Golden opposite, in which he realises that there's someone as equally as great as him, whilst the two Zoidbergs are annoyed at how their crew treats them as losers, when one of them knows where the box is and should keep it hidden away from them. Meanwhile, Fry and Leela learn more about how their secondary selves got together, in which resulted in a positive coin flip, in where it was negative for the original Leela, preventing her from dating Fry, in which annoys him.
Both Farnsworths' have been working together and conclude that neither of them are evil, and that they can return to their own universe as a result. The 2nd Professor goes into a fish tank and finds in the clam its not there, and they then find out that the Zoidberg's took it. To make things worse, the Hermes from the original universe has been sent to destroy the original Parallel Universe box, by sending it into the sun.
With the Zoidberg's running away and jumping into another random Parallel Universe box, the crew tether wire on them so that they can get back to the correct universe when they find them. After finally cornering the Zoidberg's off in the Hippie universe due to lack of boxes, the crew quickly jump back before Hermes releases the cargo lock. Farnsworth tells Hermes not to do it, in which he hesitates for a few seconds and lets them out.
The episode ends with both crews switching boxes from each universe, and as a result they both have their own existing universes with them. Everyone is watching the TV, and Fry comes in and sits on it, stretching the whole universe as a result.
So overall, a very funny and excellent episode of Futurama, using the multiple universes as a good set of jokes, and telling out the interesting outcomes of a simple coin flip. I think this episode also cleverly twisted catchphrases too, like Golden Bender's "Bite my glorious golden ass!" so that was pretty awesome. Overall, a decent episode not to be missed!