Green’s Dictionary of Slang

1. used to indicate immediacy, suddenness.

1862

H. Clifton et al. [perf. Harry Clifton] ‘Dark Girl Dressed in Blue’ 🎵 I thought 'twas a sin as I gave them the tin / And away went five pounds smash.

2. a general intensifier.

2000

J.J. Connolly Layer Cake 190: The whole place’ll be smash-alive with cozzers, heavy mob.