Mongregating
A group of people totally unaware that they are causing an obstruction and inconveniencing others trying to pass them
Look at them mongregating on the canal towpath
Mongregation
A collection of mingers similar to a pride of lions or a shoal of fish.
Person 1: "Ewww...this place is full of mingers"
Person 2: "Yah, it's like a total mongregation in here"
Person 2: "Yah, it's like a total mongregation in here"