squabble
A small, silly argument about something unimportant.
A squabble is a noisy argument about something minor or unimportant. When two friends squabble over who gets to sit in the front seat of the car, they're having a brief, petty disagreement that usually ends quickly and doesn't really matter much.
Squabbles are different from serious fights. Siblings might squabble about whose turn it is to choose a TV show, but they're not truly angry with each other. The argument feels big in the moment but seems silly an hour later. Politicians might squabble over small details while ignoring larger problems. Teammates might squabble about strategy during practice but still work together during the game.
The word has a fussy, childish sound to it, which fits its meaning perfectly. When adults say children are squabbling, they usually mean the kids are bickering about something trivial. You can squabble over the last cookie, squabble about the rules of a game, or squabble over who made a mess. The key is that squabbles are minor conflicts that blow over quickly, not deep disagreements that last.