Our Biology teacher assigned us to make a rap song explaining the menstrual cycle. Here it is:

Inside the ovary, a follicle with an egg is developed, uterus lining repairs like it doesnt care.

Follicle bursts, egg released, fertilisation can occur like a formation.

Uterus lining thickens, ready for embryo if the egg is fertilised, very organized.

Egg not fertilised? Thickness not needed. It breaks down, and it is lost through the vagina.