Because I'm happy.
That's the catchy line from Pharrell Williams' song "Happy."
The singer-rapper-producer created a video for "Happy" that runs 24 hours and features residents of Los Angeles, with a number of celebrity cameos.
And young Tunisians are tapping into a viral trend, posting videos of themselves dancing to the song.
The clips have been criticized as "debauchery and moral decay" by conservative religious groups who disapprove of young Tunisians dancing to the pop song, according to the Magharebia news website.
Magharebia says the first Tunisian video was shot in Bizerte and had over 177,000 views on YouTube.
Tunis, Carthage, Sousse, Monistir, La Marsa, Kairouan — all have videos of their residents dancing.
"It's just to say that we are happy after the revolution and to make people see how beautiful our city is," said Hichem Hosny, who made a "Happy" video in Sousse. "I didn't expect that popularity. I was surprised by the impact of the video. It was fantastic."
The "Happy" video trend seems to have started in Paris. Now, videos are popping up online of people dancing in the streets of Tokyo, Moscow and even Madagascar's Antananarivo.
Take a look at some of the videos posted below.