Several examples have already been provided but 2 points might be of further interest:
1. The Nottingham writer D.H.Lawrence uses the word in his novels of the 1920's
2. Reputed to have originated from the French word 'merde' meaning 'shit'. So, to be 'mardy' would mean to be behaving in a 'shitty' manner.
I grew up in 1950's Leicester where it was in common use.
'She's gone all mardy'.
He's being mardy because he can't get his own way.'
The handsomest of all men. A sweet, kind, wonderful and pure soul. He is considerate. Generous. The kind of person you want to always keep in your life. He is purely wonderful.
Come meet Mardie. You’ll never meet anyone more pure.
When somebody doesn't offer you a marshmallow, when they have a huge bag on their desk.
Lorna: Is James been mardy today?
Kelly: Not sure, why do you think that?
Lorna: Cos he's had that huge bag on his desk, and not offered me one all day.
To be surly. Not getting along with someone. To stop talking because you're annoyed.
Comes from Yorkshire.
to be angry and lose your temper
don´t have a mardy you moody twat
A leicester word meaning not very happy and being quite or bitchy.
hard to think of an example.
Arctic monkeys mardy bum.