Like many people who design digital experiences today, my first experience with a screen was a video game console. When Super Mario 64 came out, I remember discovering that I could warp Mario's face on the opening screen. You could bob his head to music. Nod his head in answer to a question. Twelve-year old me was delighted. The same delight that you feel when you are sucked into a game could be harnessed to create delightful UX. As designers, I think we spend too much time trying to create something slick, shiny, and expensive-looking that we forget to delight the user.
One way we can go about this is through gamification. Apps like Nike+ and RecycleBank use achievements to motivate users to do things like exercise and recycle. While they keep you motivated with badges and awards, you completely forget about those ten pounds you shed from running IRL. Users want to play, and the desire to be at the top of the leaderboard can be a powerful motivator. If apps like ChoreWars can motivate roommates to clean their toilets for experience points, anything is possible!
Playfulness isn't just about motivating the user. Sometimes it is the little moments of surprise that can cause the most delight. Subtle animation, hidden easter eggs, and witty microcopy on a 404 page can all be opportunities for delight. These subtle interactions with our users leave them with a positive feeling for your app, and if you can get a laugh? You might just have a lifetime user on your hands. I know you people are playful because you have wonderful imaginations. So quit printing out Jeff Goldblum signs for the bathroom and use that playfulness in your UX!