Macy and Polly (currently potty training and often without pants) were playing outside and I heard Macy shout:
"Mom, Polly's showing her bum!!"
Me: Polly put your panties back on.
(she likes to strip down)
"No mom, her panties are ON, but they are up her bum,
so she's showing the BOOB of her bum."
In walks Polly with quite a cute little wedgie.