Today is Maundy Thursday. We actually don't know with complete certainty the reason it's called Maundy, although the majority view is that it comes from the Latin for John 13:34, Mandatum novum do vobis ut diligatis invicem sicut dilexi vos, "A new commandment I give to you, that you love one another as I have loved you." which is associated with the day. A minority opinion holds that it instead derives (via French) from the family of words related to mendicare, to beg. So it's either Mendicant Thursday or Mandate Thursday, take your pick. But even if the mendicare etymology is right, it's the Mandate that people remember.
I remember once long ago, days of yore when I was just a boy, we attended a Southern Baptist church in Carlsbad, New Mexico, and at one evening service, a musician named Tony Elenburg gave a concert. The two songs I remember from that night both had to do with Holy Thursday: "It's Just the First Farewell" and "Wash Their Feet". The chorus of the latter, which is about the context for the Mandatum, I remember very clearly. I was curious as to whether it could be found online, and as it turns out, you can listen to it free at MySpace Music. Not the most extraordinary of musical compositions, but after all these years I still remember it from that night, so it made a mark.
The Maronites call Holy Thursday the Thursday of Mysteries, because it is the origin of the Eucharist and also of Holy Orders (while Protestants read the foot-washing as a general sign of service and often as a symbol of the Crucifixion, Catholics have also traditionally read it in light of passages like Exodus 30:17-21 or 40:30-32, and thus as the beginning of Christ's institution of the priesthood).