Khloé Kardashian clearly LOVES being an aunt!

The 31-year-old shared photos of nieces Penelope Disick and North West as well as nephew Mason Disick having a ball in some festive PJs on Christmas day.

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In a particularly adorable moment, two-year-old North, who just became a big sister, applies lipstick to the reality star's face. Looks like she inherited mom Kim Kardashian's love of makeup!

Scroll through the gallery below to see all of Khloé's Dec. 25 pics!