In the song Sugar Mice, Fish explains that "daddy took a raincheck". A 
raincheck is something that is given out:

        -  At events when it rains, like a baseball game.  Usually it means the
        game is being cancelled at the current time, and the raincheck will
        allow you into the rescheduled game.

        -  When you go to buy something at a store and it is on sale.  If
        something is supposed to be on sale, but it's sold out, they can
        give you a raincheck to pick the item up later at the sale price.

        -  When talking about social occasions, as in "Would you like to come
        over for a drink?" "No thanks, I'll take a raincheck"
        meaning either a) Can't do it right now, how about later.  or b) a
        polite way of saying bugger off.

Fish's use of the term "raincheck" goes even further.  "Your daddy took a
raincheck", implies that "daddy" has no intentions of fulfilling his duties
and living up to his responsibilities (as a father?) at this time.  (And
perhaps never will in the future either...)  This is a key point.   Daddy
is bowing out to his real or perceived pressures and leaving without any
excuses or other reasons.  He just can't cope with his responsibilities, so
he takes a raincheck.  So mom is left to raise the kids on her own, and
left to explain to the kids why dad left.  Dad at this point, has lots of
problems of his own, and is a victim of society. He lost his job and spends
all of his time at the bar ("I'm number one at the end of the bar")... He
took a raincheck...  Quite the powerful imagery, really...