Today, I got the hint to take a deeper look into the AD. Surprisingly I found the following entry in the Active Directory Schema:

Sounds like a joke, doesn’t it? If you have a look into RFC 1274 search for section 9.3.5. There you will find

9.3.5. Favourite Drink

The Favourite Drink attribute type specifies the favourite drink of
an object (or person).

favouriteDrink ATTRIBUTE
WITH ATTRIBUTE-SYNTAX
caseIgnoreStringSyntax
(SIZE (1 .. ub-favourite-drink))
::= {pilotAttributeType 5}

Seems like it is no joke at all…