In a fanfiction I'm writing, Pinkie actually pulls her own cutie mark balloons off and inflates them for a party. Twilight is aghast that Pinkie effectively made herself a blank flank, staring after Pinkie blankly. Then Pinkie grabs Twilight from behind and spins her around. Her balloon cutie mark is back, and there is no sign (other than the balloons) that Pinkie was ever pulling off her cutie mark.
So, you'll pardon me for believing that she's done just that with one of her own cutie mark's balloons~