rathole
noun
1
a
: a rat's burrow
b
: a hole gnawed by a rat
2
a
: a narrow opening, tunnel, or passageway
b
: a cramped space (as for storage or living quarters)
especially : one that is oppressive or filthy
cooped up in a rathole like this 
Jack Ward
Jack Ward 3
: a seemingly bottomless or unfillable hole
his last pile of money … went down the rathole when he tried to save an old friend from bankruptcy Stanley Walker
Stanley Walker