Shaabi is the name of a style of living, a style of dance, and a style of music.
The word is Egyptian Arabic and refers to the poorer, commoner sections of the city. An English equivalent might be "ghetto." The name came to characterize the style of music enjoyed in such neighborhoods. The style is somewhat rougher and more playful than the rest of Egyptian pop music.
Naturally, the style of dance acquired the name "shaabi". The dance is more assertively sexual than is ordinary Egyptian dance.