Brahmin Herd (Fallout)

Brahmin herd is a special encounter in Fallout.

For this encounter, you come across a herd of five wild brahmin. They say "moo!" or "moo, I say." without attacking the player and leave as if nothing had happened.

This special encounter is very hard to find and more rare than others, even with 10 luck.

Behind the scenes
This encounter was inspired by a prank Tim Cain used to play in the MUD Darker Realms, where he would teleport cows who had similar dialogue into a friend's work room. A similar joke is present in Blizzard's Diablo, when played with Hellfire add-on.