Green’s Dictionary of Slang

hot potato n.1

also hot potato jacket, hot spud

1. [early 19C+] (orig. US) a problem, a difficult person, a trying situation, anything those concerned would prefer not to handle.

2. in attrib. use of sense 1, problematic.

3. [late 19C+] (US) an admirable, clever or energetic person [hot adj. (8b) + potato n. (1)].

In exclamations

take a red-hot potato! (also hold your hot-potato!) [the effect of a red-hot potato in the mouth]

[mid-19C–1920s] be quiet! shut up!