Note that the word "Digga" actually has a meaning in German which the artist wasn't aware of:
Literally a german word, she is just in touch with the youth.
https://twitter.com/Tamithewamy/status/1770086038699950411
i didn't even know that lmao
https://twitter.com/dingotoad/status/1770102537867202897
Reddit: Is Digga considered a bad/swear word in German?
Dicker can mean "big guy" in the sense of being overweight, but calling someone "dick" isn't necessarily an insult. It's just the opposite of "dünn" (thin). Calling people "fett" or "dürr" on the other hand has an insulting connotation that "dick" and "dünn" lack.
Another things to consider is that "dicker Freund" doesn't necessarily mean "fat friend", it can also mean "very good friend" in the sense that the friendship between you is thick/strong.
In practice Dicker/Digga is just "bro" and applies to guys of all body types alike. In a similar vein, Alter can be used to mean "bro", and applies to guys of all ages, not only old men.
https://www.reddit.com/r/German/comments/ggtgd2/comment/fq508lr/