Green’s Dictionary of Slang

mehawn! excl.

[Irish mo thón! my arse!]

(Ulster) nonsense! rubbish!

[Ire]Irish Times 10 Mar. n.p.: The man from Belfast was in scathing mood [...] ‘Come to Belfast and have a look at our trams if you want to see real stream-lining. Stream-lining, mehawn!’ [BS].