This has been the basic formula for cameo appearances on SNL for many, many years. It was a little more simplified this time around, though. Typically, a cameo like that happens after an SNL cast member has made their impersonation a recurring bit from week to week. On the cameo night, the cast member will make an especially big ass of themselves in character, and then the real person will come out with a serious look on their face. The cast member will act like they're in big trouble, and it always gets cheap laughs. It's usually very short, like PSY's appearance, and the person doing the cameo typically has one or two lines at most. I've seen some comedians or the musical guest do a full sketch cameo, but that's pretty rare. I agree that it could have been more entertaining. There wasn't much to work from with their usual formula, and they basically went with the "hey kids, see how cool we are?" angle instead of trying to write something with more comedic substance.