It all depends on what the true nature of the relationship is and what the message is that you want to convey. If you’re solely sex buddies, a Christmas gift would be weird…unless it’s something suggestive. If you’re genuine friends, which means you hang out regularly and do things for the sake of doing them and not just to get to the sex part, then a gift could be OK. Again, it depends on what it is, how much it costs, and what the message is behind it. If you don’t want to risk appearing like you’re gunning for a real relationship, stick with non-personal, low-cost items, like something for his bar or a book about his favorite film director or something. Nothing that he would wear. And nothing that you made.
If you do want a real relationship and you’re hoping a gift will propel things in that direction, you better be prepared to give up the “benefits” part of your friendship. Any guy who’s got a FWB he doesn’t want a relationship with will hightail it the second he gets even a hint that she’s hoping for more. If you do want more, you shouldn’t keep sleeping with him for less. Eventually, you’ll resent that you’re settling and you’ll start to feel used. So, find out if he’s on the same page and if he’s not, MOA. The best way to find out how he feels, is to just ask him. If you like the answer you get, then think about what to get him for Christmas. If you don’t, then save the money and take yourself out for drinks