flare-up: a situation in which something such as violence, pain, or anger suddenly starts or gets much worse
run with something: to accept something, start to use it, and develop it further
rock-bottom (emotional rock-bottom): at the lowest possible level
slingshot: to cause someone or something to suddenly be in a particular situation, area of activity, etc., or to suddenly be in it
running joke: a joke/gag that is repeated many times in slightly different ways