The fall of former Egyptian president Hosni Mubarak in a popular uprising and the killing of al Qaeda chief Osama bin Laden in Pakistan have been the hottest topics of 2011 on Twitter.

The Japanese earthquake and tsunami in March has been ranked third in the list, according to the microblogging site which has released details of the hottest topics in a range of subjects, including the most talked about actors, countries and news topics.

The January 8 shooting of Gabrielle Giffords, the Arizona Congresswoman, was the fourth hottest topic on Twitter, which was followed by the death of deposed Libyan dictator Muammar Gaddafi in October.

Twitter has also revealed the year’s most popular hashtags, which are used to group together tweets relating to the same subject.

Top of the list was #egypt, followed by #tigerblood.

The first refers to the Egypt uprising while the second refers to a comment made by actor Charlie Sheen, after he was fired from his role in popular series ‘Two and a Half Men’

Sheen made the headlines in 2011 for a series of often rambling public rants which culminated with the comment to online celebrity gossip site RadarOnline: “My fangs are dripping tiger blood.”

At the same time, he joined Twitter and racked up one million followers in the first 24 hours, believed to be a record for the site, the BBC reported.

In the food category, the McLobster took top place after it trended on rumours that fast food chain McDonald’s was to roll out the crustacean-based sandwich across the US. Earlier it had only been available in Canada.

As well as featuring in the top hashtags, Charlie Sheen’s off-screen antics also moved him to the top of the most talked-about actors, followed by Macaulay Culkin, whose latest movie ‘The Wrong Ferarri, A Screwball Tragedy’ was entirely shot by an iPhone.

British talent in the top 10 including Ricky Gervais, off the back of his controversial Golden Globes appearance, Colin Firth, who won the best actor Oscar for his performance as King George VI in The King’s Speech and Pete Postelthwaite, a British character actor who died in 2011.

“Among other things, we saw history unfold in the Middle East, mourned the passing of Elizabeth Taylor, celebrated National Whipped Cream Day, and cheered for the Dallas Mavericks, Texas Rangers and Wayne Rooney,” Twitter said in its official blog.

“More than anything, these trends demonstrate how Twitter connects people with common interests. Instead of watching the news, the Super Bowl and Pretty Little Liars at home alone, we watched them together on Twitter,” it added.

A teenager who was unknown at the start of the year topped the music list. Would-be popstar Rebecca Black was propelled into stardom when her debut single Friday was released on YouTube to widespread mockery.

At the time of its release, the song ranked top in global trending topics on Twitter, surpassing the Japanese earthquake crisis.

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