Green’s Dictionary of Slang

(Irish) to tease, to fool.

1836		‘The Maid of Hungerford, And Dan the Bottle-Washer’ in Flash Casket 88: Sing hey, sing oh, how the folks did grig her, / For every day this Maid grew bigger.
1855		T. Haliburton Nature and Human Nature I 173: That word superiors grigged me.
1922		Joyce Ulysses 695: You’re always in a great humour she said yes because it grigged her because she knew what it meant.
1961		(con. 1890–1910) ‘Flann O’Brien’ Hard Life (1962) 90: As they say in Ireland, you are only trying to grig me.
1981		(con. 1920s) P. Crosbie Your Dinner’s Poured Out! 220: greg to tantalise.
1987		C. Nolan Under the Eye of the Clock 75: Yvonne [...] gregged her brother about his not being able to eat toast in bed.