The act of marking one's significant other on Twitter through cute, flirty mentions and replies, so as to make evident to others that there is a relationship in existence. Akin to a dog peeing on a tree, this is a person glittering another.
A riff on the "glitter" technique some women use to physically mark men with glitter (wear glittery cosmetics, hug/kiss, it rubs off on him, and if he shows up to another woman--she knows there's another woman already in his life).
Lynn Twitter Glittered Edward last night with her seven @ replies. They're totally dating.