Erträum is a fascinating and unique word in this song because it appears to be a creative play on words, combining "Traum" (dream) with the prefix "Er-" which often implies an outcome or a mistake (as in "Irrtum" - error).
In the context of the lyrics, "Für mi ist das ein Erträum, denn du bist gar nit erst im Raum" (For me, this is an 'Erträum', because you're not even in the room), it suggests a dream that is either flawed, mistaken, or perhaps a dream that has gone wrong. It perfectly captures the feeling of disillusionment and the realization that a past relationship or a desired reality is no longer present, making it a very engaging and memorable word for learners.
"I Trink Auf Mi" is a Bavarian dialect breakup song about moving on and toasting to your own recovery.
The singer raises a glass to themselves because they have finally gotten over an ex who never really cared. When that ex writes to say they miss the singer, the reply is blunt: the singer barely even remembers who they were.
The second half turns the tables further. The ex didn't care about hurting the singer before, so their sleeping around isn't the singer's problem anymore. Instead of dwelling on it, the singer just pours another round and drinks alone, content and free.