I know many such songs but I can't remember them all right away, here are some I can think of:
Scandal - Taiyou Scandalous: "Nanana"
Scandal - Yoake no ryuuseigun - "wo oh oh"
Kumi Koda - LALALALALA: should be obvious
Ayumi Hamasaki - until that day: "uh lalala, uhuh"
Ayumi Hamasaki - +: "La La La"
4 Minute - wait a minute: "Lala lalala"
I really like lalala for some reason.