The meaning of "toz" seems to vary greatly depending on the context. In French-language slang, which borrows a lot from Arabic, it can serve as an interjection for oral, especially among young people.
The gesture, accompanied by a raised finger, can also be much more offensive than a simple interjection, and could mean "go and make you see" The Quebec singer came in 16th place in the music competition won by Sweden's Loreen, with the title "Tattoo"