"Hermione's friends always warned her that her curiosity would get her into trouble some day. Something they conveniently 'failed' to warn her about however, was the highly-customizable anti-tampering spell, cast on all their presents.
And so, after a single pull on a ribbon, any complaint swiftly silenced as her panties filled her mouth, Hermione got to spend her Christmas Eve as the newest gift under the tree.
When the girls awoke the next morning to open their presents, they made sure to save the biggest one for last."