An insult to someone's intelligence or ability, or describing an individual who is struggling to keep up with the rest of the pack
. A 'cold shot' refers to a steam-catapult launch from an aircraft carrier when the steam pressure is too low for the launch weight of the aircraft; on reaching the end of the deck, the aircraft is going too slowly for safe flight and may drop dramatically, or even (in extreme cases) ditch. If ditching is avoided, there follows an agonisingly slow climb away with the handle jammed forward and all the gauges pegged in a desperate attempt to gain height and speed.
When a lowlife person or group entity of people abandons one particular foul interest or behavior for one even worse, such as flies would abandon a mere pile of shit for a foul-smelling, bloated and rottedcarcass.
"All of today's Republicans adore Donald Trump and want to become more and more like him every day, so they sure as hell ain't gonna be flying off the shitpile just for a moderate conservative like you!"