Green’s Dictionary of Slang

squash v.

1. (US) to sort out a problem.

[US]Ersine Und. and Prison Sl.
[US]C. Stoker Thicker ’n Thieves 179: Sergeant Elmer V. Jackson [...] made a ‘plant’ of a gun on one of his henchmen and demanded twenty thousand dollars to squash the beef.
[US]R. Woodley Dealer 100: ‘Now you can take him to jail if you want, but I’d like to have this thing squashed’.
[US]Bentley & Corbett Prison Sl. 16: squash To straighten out, to take care of or stop something.
[US]Source Aug. 47: I once found myself in a sticky situation where I had to try and squash beef for a client who was involved with a [gang] from the other side.
[US]Woods & Soderburg I Got a Monster 58: ‘We squashed it. We shook hands at the end, so we all good’.

2. to crush verbally.

[UK]A. Liddell Hart Strange Company 54: [T]he only times when he seemed to get really annoyed was when someone began to make disparaging remarks about another person’s nationality. [...] [I]t was his job to squash such an attitude .
[US]Eble Campus Sl. Apr. 5: squash – put an end to.
[US](con. 1990s) in J. Miller One of the Guys 86: ‘If they get into a scrap [...] we make ’em show love anyway. Just tell ’em to squash it’.

In phrases

get off the squash (v.)

(US) to have sexual intercourse.

[US]V.F. Nelson Prison Days and Nights 27: They want to get off the squash, so they fix it up with this white broad to take on the whole four of them.
put the squash on (v.)

(Aus.) to forbid, to terminate.

[Aus]Sport (Adelaide) 10 July 4/2: Who put the squash on Jack R’s vists round to see R/S. [...] her father?

In exclamations