To step up from the all the trolls and shitposts
This is what the German Wikipedia says.
Basically another code which is printed on the Package/Letter etc. to speed up the mechanic sorting and forwarding.
You are not going to die nor are you target by anyone who tries to kill you
Well, as long as the machines dont take over you should be safe.
Add "MPGH" when adding me!
If not I will block you to avoid spam.
Do not add me if you need SE related help.
There are enough Step by Step Tutorials in the Social Engineering Section