Green’s Dictionary of Slang

earhole n.

1. [mid-19C+] the ear.

2. [20C+] a toady, a sycophant.

3. [1960s] an act of listening, of eavesdropping.

In phrases

on the earhole (also on the Happy New ’Ear) [one is talking into a victim’s earhole]

[1910s+] (UK Und.) on the scrounge.