This will kill them and sometimes you.
I was laying in my hammock one day, and I see this red squirrel walking along the top of the fence towards me, and he knew I was there perhaps five feet away, and kept pausing, staring at me, chattering, twitching his tail, but...I didn’t move a muscle.
So, he’s up there doing that annoying red squirrel thing, and I snapped my fingers.
If you had stuck him in a 105 mm howitzer shell and fired it, it wouldn’t have disappeared from view any faster than that squirrel did!
For aggressiveness per square cm of flesh, they must rank up there with chickadees and honey badgers!