The Syriac Orthodox Church celebrate the Annunciation of the Virgin Mary today (March 25th). We have a tradition that I believe is only done in our Church where we put on a so called "siboro" around our wrist. This "siboro" consists of a white thread and a red thread winded (I hope this is a real word) around each other.
When Virgin Mary became pregnant the Divine nature (God the Word; the white thread) united with the human nature (the red thread) which God the Word took from Virgin Mary through the holy Spirit's action. One Nature was formed, etc. You know the drill.
We wear the "siboro" from March 25th (the Annunciation of the Virgin Mary) until Easter Monday (or Easter Day) when we clip it off and burn it.