Informing another party that a certain object, personality trait, person,
dinner bill, bar
tab, human
baby, etc that does not belong to you OR would like to attempt to distance yourself from.
Waitress: "Thanks for coming in, guys. Here's the bill."
You: 'Ain't my
baby". (friend pays the bill)
Doctor: "Congratulations, it's a boy". You: "Ain't my
baby."
Cop: "Who's bag of booger sugar?" Kev: "Shit that ain't My
Baby.'