滚瓜烂熟

滚瓜烂熟

Literally means:

a fully ripe melon would roll away from its pedicel; have memorized something thoroughly.

Actually means:

滚 here means a melon falls off the vines.This phrase literally means as ripe as a melon falling off the vines.

It figuratively means having well memorized something from the book or from other sources and can recite it very fluently. It is commendatory.

滚，这里指瓜从藤上掉下。滚瓜烂熟，像从瓜藤上掉下来的瓜那样熟。

形容对书或其他事情的内容记得非常牢，背起来十分流利。具有褒义色彩。