I guess in Germany there is/was this Jugendbonus, where the government just gives kids money every year? Sounds Alaska-level crazy socialism, I know, but whatever. You only get it until you turn 20, and have to do national service, and so I guess Abschied vom Jugendbonus [Farewell to Jugendbonus] is like a mourning for the carefree good old days?
None of which directly relates to why a dejected Martin Kippenberger is wearing a diaper with a Keith Haring Radiant Baby on it, since by 1984, he was already like 31. I'm going to guess he was just striking a pose, making a point about the mythologization of childhood and the reluctance to grow up.
But that's just a guess. Haring's pure brand marketing these days, so maybe by taking it seriously, I'm the one clinging, dumb & nostalgic, to the past.
Heres some remarks from Germany:
What you probably are referring to is called "Kindergeld" (literally Money for children). Its in fact Money from the State to support you raising your children. It will be paid to the parents until their child finishes its school career and or first job training. Kindergeld differs by the number of children that you have, but for the first child it is nowadays roughly 250$ per month. I dont know about cost of living in NY, but in a typical bigger German city this wont bring you too far, especially when the kid grows up (think college tuition)...
Now for Jugendbonus: this has nothing to do at all with Kindergeld, but might be referring to "being excused for doing something because you were young (and foolish)"... There is (was) a saying "ich war jung und brauchte das Geld (i was young and needed the money", which was once maybe a good and valid excuse (for lets say Madonnas nude pics as a young girl). But its nowadays used more in a fun way to bring up an excuse for all kinds of stuff. Which is probably also the Idea behind the title in this case: Say goodbye to Jugendbonus
By the way: there is no more duty to do national service these days in Germany. But of course there was in 1985. I dont know about both artists, but there was a Lot of artist Bohème ar that time in Berlin who fled the duty call (the army MP was not allowed to go to Berlin and pull you back to boot camp).