It's an acronym. Trump Always Chickens Out. A financial analyst used it to describe trends in the market. Trump threatens something stupid, Trump tries to do something stupid, Trump is threatened with any sort of negative repercussions, Trump Always Chickens Out.
Note that he has to personally face repercussions. Everyone else can get fucked, as far as he's concerned.
A reporter asked him about it, and he started whining like he needs a diaper change. This made it more of a story, like the Streisand effect.