Green’s Dictionary of Slang

sorry and sad adj.

bad.

1960		J. Franklyn Dict. of Rhy. Sl.
1971		J. Jones Rhy. Cockney Sl.
1978		Maledicta II:1+2 (Summer/Winter) 119: (Even in America we have picked up examples you may not have noticed as such: brass tacks = facts in ‘let’s get down to brass tacks’ and sorry [and sad] = bad in ‘what a sorry sight.’).