Firm up those Christmas travel plans and put all your important communications in writing. And do it quick! This Sunday, messenger Mercury turns retrograde in Sagittarius — the sign that rules travel and uncensored truth — until December 22. Take a deep breath. This news doesn't have to dampen your festive spirit. But to avoid any intergalactic Grinchiness, clear, kind, and compassionate communication is key. Make no assumptions! Did you actually request that extra day off from your boss? Are you sure it's cool with your sister if you crash on her couch? Err on the side of over-communicating, even if you annoy a few people in the process. But here's where we should all censor ourselves until the 22nd: Doling out unsolicited advice and backseat driving (especially on Twitter). Those truth bombs might be spot-on, but timing is so off.