Green’s Dictionary of Slang

1. (Irish) short [butt n.¹ (1a)].

1922		Joyce Ulysses 241: He looked butty and short in his shirt.
1997		Share Slanguage.
1999		D. Healy Sudden Times 167: We landed among a bunch of butty planes.

2. muscular.

2006

P. Shannon Davey Darling 216: ‘Did it feel like a woman’s leg?’ ‘Well, it wasn’t all butty and hairy like a man’s leg,’ I said.

3. (N.Z. prison, also buttie) large, fat; generous.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 35/1: buttie adj. big, fat, generous.