Given that the people were rather laughing than being startled, it means they have likely seen or heard that they were kids (fast moving light steps, gloating sniggering) which you missed.
No, it is not common at all, you are simply unlucky to experience it.
No, this is not a common occurrence in any part of Germany.
Looks and sounds like a silly prank.
Credit:stackoverflow.com‘
4 Mar, 2024
5 Mar, 2024
4 Mar, 2024