On the lash

v.

Heard in Dublin, Tipperary, Waterford and Galway

To go out drinking heavily.

In use

I was on the lash last weekend and I got so shit faced I don't remember how I got home

Posh English

I was on a considerable drinking binge last weekend and became so thoroughly inebriated that I have no recollection of how I reached home.

Same phrase, other counties