"Plain" is a song by New Zealand singer-songwriter Benee featuring British singer Lily Allen and American rapper Flo Milli, released through Republic Records on 27 October 2020 as the third single from her debut studio album Hey U X (2020).
The release of "Plain" was preceded by the singles "Night Garden" and "Snail". On the motive behind the track, Benee told NME:
The song was released as a surprise release with no prior announcement on 27 October 2020 by Republic Records.
Musically, "Plain" is an alternative pop song that contains "glossy, rolling, trap-heavy beats". The song was described as "self-assured" with its "dreamy guitar hook" and a "thumping beat". Chris DeVille of Stereogum drew comparison between the song's "foggy, blippy, chillwave-adjacent mood" and that of "Clairo with a trap beat". He noted that "the sonic soup is a great environment for Benee, even if it somewhat blurs her voice together with Allen's and therefore obscures the flex of featuring her alt-pop forebear on a song. No such trouble with Flo Milli, who adds a burst of enthusiasm to the track upon arrival." Sose Fuamoli of Triple J described "Plain" as "a message to the ex, delivered with sass and dreamy sounds." She praised Allen's featured verse, describing it as "a beautifully melancholic one" and that by "coupl[ing it] with Benee's already captivating style of vocal delivery, bringing Lily into a song like this feels like a natural flex." Towards the end of the track, Mike Wass of Idolator wrote "Ouch! It turns out the song is meant to be a raised middle-finger to an ex."