When I was a teen, I worked in the stock room of a boutique. It was a ‘glam rock’ kind of place and I was more ‘crunchy’ so ‘the back’ was the right place for me. The sales girls were attractive and threw attitude ‘out front’ but in the back they were smart and quite fun.
Anyway, two of them had plans to hit the town one night (Saturday) but as evening approached, a hot guy asked one out and she immediately accepted. She was happy.
Crunch: Don’t you and Val have plans tonight?
Glam: Yeah, but she’ll understand. If you can’t diss your friends, who can you diss?
Unfortunately, that’s not exactly what she said, but I assert that that was the thrust of it. 
BTW, the shop slang for ‘crunchy’ back then was ‘brown rice’ or ‘granola.’