Sandra's trying to make Robbie horney? Sandra thinks Robbie is horney? Sandra knows Robie is horney and likes to tease him? Why didn't Sandra send me a reindeer?
Traditionally, when a man received a "gift" of horns, that was the sign that he was a cuckold - a married man whose wife is cheating on him. This comes from the idea that the man was wearing the horns of a cuckold; horns he can't see but everyone else can. (In some towns in Eastern Europe, the community would gather to humiliate a man whose wife just gave birth to a child demonstrably not his, presumably by presenting him with a set of horns) The term, as I understand it, comes from a certain variety of cuckoo bird who does not like hatching eggs and so, having given birth, deposits her eggs in another's nest.
Of course, sometimes a gift of horns is just a gift of horns.