Stomach.
Last night, I was invited over to my buddy's house for dinner. As soon as I sat down to eat, I found out that it was going to be a practice night. It didn't bother me at all. In fact I was howling at how deceptive he was about it all. Either way, it didn't matter whether I knew or not; good thing I didn't have any set plans that night. I can only guess that my friend didn't tell me about the practice because I guess he didn't want me to bring my upright bass over. Either he wanted me to focus more on the vocal arrangements or he's being subtle about how I play my bass. Either way, that's a clever way of getting a practice together.
