What is Twash?
1.
Twash, a corruption of the word "twat", meaning a womans genitals or an annoying person.
"fuck off you twash"
or
"you lick her twash"
2.
Corruption of the word "Twat", meaning a womans genitals, also used as an insult. Was first used to insult a Welsh teacher, who put the "-ash" suffix on every word she could, for example "Put thash pencil down!"
In a sexual manner:
"Mark would love to lick Nina's twash, but he has a bird"
As an insult:
"Piss off you twash"
See
3.
A combination of the name "Josh' and the word "Twat"
When someone's name is Josh, and they're a twat, they become a Twash.