Green’s Dictionary of Slang

ass-wiper n.

[ass-wipe n.; cf. earlier arse-wiper n.]

1. a sycophant, a toady.

[US]Baker et al. CUSS 72: Ass-wiper One who does organization’s dirty work so as to advance.

2. something extremely difficult, demanding.

[US]M. Braly On the Yard (1977) 32: You look like you kicked an ass-wiper [i.e. heroin addiction].