many's the (something)
There are or have been many such occasions. Refers to units of time, as in "hour," "day," "evening," etc. Many's the evening I've thought fondly on my time as a teacher in rural Japan. When you're young, many's the hour you spend playing with friends, blissfully ignorant to the troubles of the world.
many's the
— used to indicate that something happens often. 2000 Taxi News Many's the happy hour I've spent listening to cabbies thrash that one out.