Britney wishes her fans "Merry Christmas" in March

Britney shook things up again at her concert in DC. Britney was in the middle of her concert while singing when she shouted out "Merry Christmas!" (00:50). The fans went wild until they realized it is March and you hear them saying "What the f*ck!" This could be a way Britney just likes to have fun and poke at the people who make fun of her for lipsynching. Maybe she wants to show them, hey, I am Britney Spears and I can do whatever I feel like.