Green’s Dictionary of Slang

squat n.1

1. a seat, a chair.

[US]T.A. Dorgan in Zwilling TAD Lex. (1993) 130: There are 500 seats on it and at $5 a squat you can clean up on the day of the naval parade.
[Aus]Bulletin (Sydney) 25 Aug. 15/1: Owing to the surplus of eaters over seats, immediately the tin is walloped there is a stampede for the festive board with a prologue in rainbow language from the ‘also rans.’ But Peter’s squat is always immune from assault, and the nigger waiter [...] always delivers Peter’s plateful ‘first time.’.
[US]T.A. Dorgan Indoor Sports 26 Mar. [synd. cartoon] This show wouldn’t fill 3 rows in a sawmill town. Two bucks a squat too.

2. (US teen) the vagina [? deliberate euph. for twat n. (1)].

[US]‘Paul Merchant’ ‘Sex Gang’ in Pulling a Train’ (2012) [ebook] She’s always got a hot rash. [...] Your’re lucky she didn’t tear you aprt with that hot squat of hers.

3. (US) an act of defecation; also, of women, an act of urination.

implied in take a squat
[NZ]McGill Reed Dict. of N.Z. Sl. 98: have a squat To defecate and also, female, to urinate. ANZ.

4. (US) excrement.

[US]Chapman NDAS.

5. (US prison) the electric chair; electrocution.

[US]Bentley & Corbett Prison Sl. 105: Squat The electric chair or electrocution.

In phrases

take a squat (v.)

to defecate.

[US]L. Heinemann Close Quarters (1987) 298: No more flies up my ass when I take a squat.
[US]S. King Different Seasons (1995) 398: I was gonna squat when we got across, anyway. I hadda take a squat, you know?
J. Worley ‘An adjustment’ 11 Nov. on Aiding and Abetting [Internet] ‘We’re gonna have to total your car,’ he said. ‘There’s no way to fix it?’ I asked. He fixed me with a serious stare. ‘You were driving a 1990 Acura Integra. If a bird took a squat on that car, we’d total it.’.