At least they know him
Work Secret Santa is always challenging – we don’t really know our co-workers well enough to know what they’d want as a Christmas gift, but we don’t want to buy them something too banal. This person figured the safest thing would be to buy his Secret Santa partner a shirt they’ve seen him wear before. Of course, they didn’t expect him to wear the said shirt to the Christmas party.
Being consistent is good, but it’s a thin line between being consistent and being boring. You don’t want to be the guy who always wears the same shirt. At least it means his coworker knows him pretty well, which is nice, right? And he doesn’t seem disappointed by the gift, on the contrary, he seems amused.