Used as an adjective to compliment something. Pin-drop's origin can be traced back to the common saying "pin drop silence"
When the silence is at its maximum, you can hear a pin drop.
It was later adapted to mean the ultimate/best form of something. It was popularised by music teachers from the 80s to compliment an amazing performance that led to a gobsmacked audience at the end of it.
That music performance was pin-drop worthy
The food here is pin-drop
Yo! Those sneakers are pin-drop
That's a pin-drop sky
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.