The US presidential campaign may be a deadly serious affair, but Americans have taken to social networks to lighten the mood with a good dose of humor and sarcasm. Here are our top 10:

- The hashtag #eastwooding went viral on Twitter after Hollywood star Clint Eastwood's guest appearance at this year's Republican National Convention, where his speech focusing on an empty chair meant to represent Barack Obama baffled many.
Obama's team eventually tweeted a tongue-and-cheek photo of the President sitting in a chair with his back to the camera, captioned "This seat's taken."

- A widely-viewed YouTube video managed to poke fun at the otherwise gaffe-free Barack Obama. The spoof lip-read of the first presidential debate mocks the President's lackluster performance.
At one point, a sleepy-looking Obama appears to be dozing on his feet. "Yep, er, he's asleep" a wide-eyed Mitt Romney quips: http://www.youtube.com/watch?v=QlwilbVYvUg

- Mitt Romney's "Big Bird" comment at the first debate featured widely on Twitter, with several parody accounts created.
"I like PBS (US public TV network). I like Big Bird," Romney said at the debate, but nevertheless pledged to cut support for public television. The Twittersphere promptly exploded. "Obama killed bin Laden. Romney would put a hit on Big Bird," @EliClifton joked.
Romney even managed to anger otherwise bored children watching the debate in one widely-viewed YouTube video. "What?... I vote for Obama anyway," one kid says angrily: http://www.youtube.com/watch?v=05uQR5C2AXw

- Hot on the success of South Korea's "Gangnam Style" song, a comedy website called CollegeHumor put out "Mitt Romney Style" on YouTube: http://www.youtube.com/watch?v=yTCRwi71_ns
Meant to poke fun at the wealthy Republican challenger, a Romney look-a-like prances around horse-riding stables and golf courses to the rhythm of the original song.
"Affluence, extravagance, that's Mitt," the lyrics say at one point in the song, as 'Romney' laughs at a waiter who has a "47%" sign hanging on his back -- a reference to his unguarded comment writing off 47 percent of the US electorate.

- The second debate also provided fodder for wanna-be online comics with Romney's "binders full of women" quip.
Asked about unequal pay, Romney responded that as Massachusetts governor, he went out of his way to add women to his staff. "I went to a number of women's groups and said, 'Can you help us find folks,' and they brought us whole binders full of women," he said.
The Twittersphere lit up, and a satirical account on Tumblr -- the blogging platform -- was even set up, featuring photos of various women holding custom-made binders: http://bindersfullofwomen.tumblr.com/

- When Obama ironically mentioned during the third debate that the army had fewer "horses and bayonets" than it did before, the Internet went crazy.
Netizens took to Twitter to joke about it, and one page on Tumblr spawned countless parody photos: http://horsesandbayonets.tumblr.com/
One shot of Obama leaning over to speak to Joe Biden features the caption: "Iran might get a nuke. Do we have enough horses and bayonets?"

- Saying the middle class had been buried over the last four years, confusing Iowa with Ohio in a speech... Vice President Joe Biden has attracted a lot of attention with his gaffes.
YouTube is full of videos putting them all together. His gaffes have even spawned a new word - "Bidenism."

- Paul Ryan also spawned a few chuckles when Time published photos of Romney's running mate pumping weights with a red cap on back-to-front.
The shots spurred a rash of gifs (animated pictures), funny blog posts and a fake Twitter account called @PaulRyansBicep. The pictures were taken in December 2011 and published in October this year -- the day of the VP debate.

- Jim Lehrer, a respected journalist, may have regretted his decision to moderate the first presidential debate this year.
By the time the debate ended, the Twittersphere was busy poking fun at the 78-year-old -- who was widely regarded as not being tough enough -- and a fake account called @SilentJimLehrer sprung up, garnering thousands of followers.

- Lastly, the Democratic National Committee set up a website mocking Romney's tax plans, which has been widely retweeted.
"For a detailed explanation of how the Romney-Ryan tax plan is able to cut taxes by $5 trillion without exploding the deficit or requiring tax hikes on the middle class, simply click the button below," it says.
But users are unable to press the button -- which reads "get the details" -- as it moves to the side every time the mouse gets near: http://www.romneytaxplan.com/