This is a bouncy, deadpan novelty indie-pop song about the performance of being delighted for other people. The chorus is the reply you have given a hundred times, arriving right on cue: "Aren't you excited?" — "Yeah, that rules."1
The verses live in the second before you answer. One is a friend announcing the job that will quietly end the friendship, delivered as good news you are expected to match in tone 1. Another is the adult birthday, which turns out to be mostly texting back "thanks!" to people you have not talked to in ten years 2. The third makes a warm case for holding a grudge, since resentment and disgust are feelings somebody earned 3. Between them comes a bridge of everybody smiling and nobody meaning it. The wording stays close to the tweets, so each joke lands the way it did in the timeline, only now with a chorus you can hum.
Play it in the car on the way home from somebody else's good news, on a Sunday evening when the group chat is quiet, or the next time a friend tells you they got a great new job in another city. The source wording and the credit belong to @PeerPressurDoIt, @Eden_Eats and @misstaabe.