the mother of all (something)
The largest, most extreme, or ultimate example of a particular kind of thing. The word that follows "of" is usually plural. Wow, that is the mother of all sandwiches. It's a foot high!
the ˈmother (and ˈfather) of (all) something (informal) used to emphasize that something is very large, important, etc: There was the mother of all storms that night. It lasted for hours. ♢ Sorry we’re so late. We got stuck in the mother of all traffic jams on the way.