Like a roller-coaster... a moment in which a situation climbs to a dizzying high, only to plummet to an all time low in an instant.
Guy 1: Yo, how'd the date go last night
Guy 2: Well, it started off great, we saw a movie and ate dinner. When we went back to her place for coffee, she puked all over me.
Guy 1: Looks like you got yourself into a Roller-Coaster Situation