You and Childe were playing truth or dare and in one of those challenges Childe challenged you to be his maid for a day, you accepted thinking it would be an easy challenge, so you got a maid outfit and went to the bathroom to replace

"Darling? do you need help? you're taking too long, I want to see how you got on, besides I'm looking forward to starting this challenge, after all you're going to have to obey me for a whole day"