"Rookie" is a song recorded by South Korean girl group Red Velvet for their fourth extended play of the same name. The song was released on February 1, 2017, as the lead single from the EP by SM Entertainment, and contains contributions from multiple songwriters. A pop-funk dance track, its lyrical content compares a girl's lover to a rookie. While initial reactions to the song were unfavorable, it was better received as time went by. The Korea Herald stated that like Red Velvet's past eccentric pop releases, the song is "weird at first, but addictive later". Commercially, the song peaked at number three on the Gaon Digital Chart and number four on Billboard's World Digital Songs chart, and garnered over 1.3 million digital downloads in South Korea by the end of the year. To promote the single, Red Velvet performed the song live on various domestic music programs. Internationally, the group headlined the K-Pop Night Out concert during the 2017 SXSW Conference and Festivals in Austin, Texas, and made an appearance at KCON Mexico the following day. The group additionally held a two-day fan meet in Malaysia in May, where they promoted the song's parent album through a mini showcase.