The song "Riff Off" from the film Pitch Perfect 2 is a medley that combines various popular songs and lyrics, resulting in a playful and entertaining performance. As a song medley, it does not necessarily have a single cohesive meaning. Instead, it serves as a celebration of different musical genres, styles, and lyrics.

The lyrics in "Riff Off" include excerpts from songs like "Thong Song" by Sisqó, "Low" by Flo Rida, "Bootylicious" by Destiny's Child, "Baby Got Back" by Sir Mix-a-Lot, "Before He Cheats" by Carrie Underwood, "A Thousand Miles" by Vanessa Carlton, "We Are Never Ever Getting Back Together" by Taylor Swift, "What's Love Got to Do with It" by Tina Turner, "This Is How We Do It" by Montell Jordan, "Doo Wop (That Thing)" by Lauryn Hill, "Poison" by Bell Biv DeVoe, "Scenario" by A Tribe Called Quest, and "Flashlight" by Jessie J.

Given the combination of these various song snippets, it can be interpreted that the song is about the joy of musical diversity and the power of music to bring people together. It emphasizes the fun and energetic atmosphere of a riff-off, which is a musical battle of sorts.

Overall, "Riff Off" aims to entertain the audience with its medley of familiar tunes and clever song transitions, showcasing the creativity and talent of the performers.