Sunmi is the queen of not giving f*cks, and I love her dearly for it! As I found out from this video, the title, "Lalalay," is a stylization of the Korean word, 날라리 (nallari, pronounced as Nal-la-ri), which is usually used in a negative context to refer to people who try to act cool through partying, drinking, smoking, etc. And in the song, she says that she's ok, no matter what people say. Maybe she's a little naughty, but she's not a lalalay. And even if she is? So freakin' what?
It's also super cool that she features a traditional Korean instrument, the taepyungso, so prominently in the chorus — you definitely won't forget it. But the message of the song is so witty and self-aware, and gets an A in my book. Just let them talk, they'll still follow you anyways — "Like a swarm of bees, wing wing / The more they do win win / I’m a small pied piper captain / On a sharp knife."