Green’s Dictionary of Slang

hot seat n.

1. [1920s+] (US, also hot settee, ...spot, ...squat, seat) the electric chair; thus, as v., to be subjected to the electric chair [hot adj. (9b)].

2. in attrib. use of sense 1.

3. [1930s–40s] any situation in which the subject, consciously or not, is exposed, esp. for the purposes of a confidence trick [note Davis, Phenomena in Crime (1941): ‘So called because the hooked “mug” is on tenterhooks re the materialization of the investments he has handed over to the crooks’].

4. [1950s+] an unpleasant situation, esp. in a courtroom or public enquiry; esp. as in the hot seat.

5. [1950s+] the seat in an interrogation room on which the prisoner sits.

6. [1960s+] any form of interrogation, in a non-official context; also attrib.

In phrases

take the hot squat (v.) (also do the hot squat)

[1920s+] (US) to be executed in the electric chair.