Tenso is a series of multi-pane images that place emphasis on an unusual or odd facial expression in a given photograph for comedic effect. Each image usually consists of several frames of a photograph that progressively zoom in on a targeted area. Sometimes, the final close-up pane reveals something that is hardly visible in full-dimension, creating an effect of surprise, similar to the when you see it, you’ll shit bricks meme.
The origin of the meme has been a subject of dispute, though many credit the Brazilian gaming forum UOL Jogos' Vale Tudo ("anything goes") board as the site of origin. Others have claimed that members of Vale Tudo simply take credit for creating it but the meme has existed prior on 4chan before being adapted into Portuguese language. The vertical panel layout is similar to other multi-pane memes like Gaijin 4 Koma and Kurt Cobain Reactions.
Beginning in late 2008, the idea started to spread to other forums and became a fad in Brazilian blogs and social media. In 2009, Fabricio Zuardi created the Gera Tenso, an image generator site that allows anyone to easily create his own version of the meme. Some Brazilian blogs started celebrating Tenso as a national meme after it entered the mainstream media in early 2009. The Brazilian humor site Oesquema  also became a central hubsite for curating Tenso images.
Tenso images can be also seen on Portuguese language message boards like Nerdorama and LevelUpGames. There are numerous single topic blogs curating the best of Tenso images such as Tenso blog and Tenso on Tumblr. Tenso Blog is another website that collects various instances of Internet humor including various viral videos and image macros, not limited to the multiple-panel Tenso images.
Although the word "tenso" is a commonly used adjective in Portugese, Google Insights reveals a large climb in searches for "tenso" through 2009, indicative of not only a viral phenomenon, but a long-standing and ever-growing cultural trend.