At the sorrowing meadows there is a place with 2bombs and a bee(?)hive.
Check the location on the screenshot. It's just next to the leftside exit.
After you reached the place, stand at where dust is standing in the screenshot, and kill the following
bees without jumping. After u got rid of the bees, press "W"key(or any key for up-arrow) to get the
hive in sight. Doing this will make the bees spawn and stack without chasing you.

Check the bottom picture.


wait for a few moments while pressing "W"key to spawn enough bees.
Then BOOM! Easy acheivement.
Equipping the ugly pendent or removing your weapon and rings is recommended for easier results.

Hope everyone gets the achievement :)