Green’s Dictionary of Slang

paddywhack n.

[Paddy n. (1) + whack n.2 (1) + negative stereotyping]

1. [late 18C–1910s] an Irishman, esp. when large and brawny; thus Paddy Whackery n.

2. in attrib. use of sense 1.

3. [late 19C+] (also paddywhacking) a severe beating.

4. [late 19C] a rage, a passionate outburst of temper.

5. [late 19C+] (Irish) stage or ‘professional’ Irishism, e.g. much use of ‘Sure an’ beggorrah, sorr...’.

In derivatives

paddywhackery (n.)

[mid-19C+] the attributes of stereotyped Irishness.

In compounds

In phrases

paddywhack the drumstick (n.)

[late 19C+] (Aus.) a spanking, a thrashing.