cluster flock 

a large gathering of birds that fly across the runway just as you start your takeoff run.

Co-pilot, "BIRDS 12 o'clock high!"

Pilot, "Oh, Shit, we're headed for a cluster flock....."

cluster flock by Scully, you're not alone January 25, 2010

Cluster-Flock 

When multiple dickheads flock into a certain, place, fandom or hobby, transforming it into a clusterfuck of assholery. They will then anally rape it until it is sore, rotten and a genuinely bad place for everyone.

Joe: Did you see what the SJW invasion did to Marvel Comics?
Rex: Yeah. Once they began cluster-flock to it, it was only a matter of time.

Cluster-Flock by Blarg-chicka-honk-honk March 12, 2018

Cluster Flocking 

The process of geese have sex in a large group, diverged from "fucking".

Dude did you see those geese?
Yeah, they were cluster flocking!

Cluster Flocking by hammerjelly June 6, 2011