Ringsend handshake, n. — Green’s Dictionary of Slang

Ringsend handshake n.

also Ringsend uppercut

[Ring’s End – a rough area of Dublin]

(Irish) a kick in the testicles.

1958		(con. 1940s) B. Behan Borstal Boy 128: A good kick in the balls [...] what they called in the slums at home a Ringsend uppercut.
1987		(con. 1920s) L. Redmond Emerald Square 81: ‘Put the boot in’. ‘Give him the Ringsend shake hands’. A knee in the balls.
1991		J.B. Keane Love Bites and Other Stories 69: The most devastating of all blows in the common street confrontation was the Ringsend Uppercut. This was simply a kick between the legs.