hot potato n.1
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)].
[mid-19C–1920s] be quiet! shut up!