The two brothers started squabbling over a piece of candy.
Tips
usage
Lighter than 吵架 (chǎojià, to fight/argue) — 拌嘴 implies petty, not-too-serious bickering, often between people who actually like each other (couples, siblings, kids). The set phrase 拌嘴斗舌 (bànzuǐ dòushé) emphasizes the back-and-forth verbal sparring.
memory
拌 means "to mix/stir" (think 凉拌 cold-mixed salad) + 嘴 (mouth). Picture two mouths "stirring each other up" — bickering is mouths churning over each other.