Go up and give them a high five, as you would normally. And by "high" five, we mean HIGH five. Not those low five things.
Don't stop there. Take advantage of gravity and let your hand continue to fall.
End by slapping their butt. As hard as you want.
See, its a very dignified act, much more impressive than what you usually do. Not too hard to carry out, either. When you get bored of butt slapping, you can try hand hugs.
Or make up something of your own, like Kylee and I did here. It is "The Supreme High Five Of Glory", but I will not tell you the whole process, it is much too glorious.