Milderin' wet

v.

Profuse precipitation, lashing rain.

In use

'Twas milderin' wet de udder day boy, I was soaked through to me skundies so I was.

Let Lawrence Muck translate it to posh English for you
Lawrence Muck

Good evening. Sherry? Would you like me to translate 'Milderin' wet' in use for you?

It was raining torrentially the other day, old boy; I was drenched right through to my undergarments.