Sow one’s wild oats

What is Sow one’s wild oats?

Sow one’s wild oats definition and meaning on Dictionary terms:
noun

any uncultivated species of Avena, especially a common weedy grass, A. fatua, resembling the cultivated oat.
a hardy plant, Uvularia sessilifolia, of the lily family, of eastern North America, having deep green, hairy leaves and greenish-yellow, tubular flowers.