18. Rae Sremmurd: 21 Under 21 (2014)

Roman Vail 
Rae Sremmurd

21 Under 21 Main Page

Birthdates: Khalif “Swae Lee” Khalif: June 7, 1995 (Age: 19); Aaquil “Slim” Brown: Dec. 29, 1993 (Age: 20)

Last year's rank: N/A

Why They're Hot: Rae Sremmurd, composed of brothers Khalif "Swae Lee" Khalif and Aaquil "Slim" Brown, took over the Billboard charts with their 2014 summer smash "No Flex Zone." The addictive track, produced by Mike Will Made-It, has been remixed by artists such as Lil' Kim, Nicki Minaj and Pusha T. The duo (whose stage name is "Ear Drummers" spelled backwards and pronounced Ray Shreh-murd) followed up the hit with yet another titled "No Type," which features the two showing love for women of all sizes and shades. Rae Sremmurd have no intentions of slowing down; the pair, who are signed to Mike Will Made-It's Interscope imprint EarDrummers, are currently prepping their upcoming EP, SremmLife.

21 Under 21's Next Class | Top 21 Songs by Under-21 Singers 

Billboard's 2014 21 Under 21 List