Hiding a surprise in a visual is a great way to make them more fun. The surprise can't be hidden so much it would take hours to find. It needs to be hidden just enough to be missed on the first glance. But easy enough to find in a minute or two.

Discovering a surprise gives the same sense of satisfaction as solving a problem. And that's what people will feel after discovering the surprise in your visual. And because they really looked at it, they will be much more likely to remember the visual, too.

So what's the surprise hiding in Santa's sleigh? Here's a hint: He's the one wishing everyone Merry Christmas, not Santa!