Similar to something being is Killer.
"Killer" is used more by people who go to the beach and have a relaxed vibe & acts like the word "immaculate" while "Banger" is more like standing out, explosive, and is more accurate to something being ideal, similar to the phrase "spot on".
"That's a banger coffee mug! Where'd you get it?"
"This song's a banger! I can't wait to follow the artist after the music festival!"
Like buyer's remorse, banger's remorse is a feeling of regret, but it comes the day after banging someone. (Slightly more vulgar than boinker's remorse.)
Pat woke up with a hangover, discovered Chris naked in the bed, and experienced banger's remorse.