Any letter you can think of can be used as a variable. They can be uppercase or lowercase. When you get into more complex math applications, you might have several variables in one equation, so your ability to use more than one variable at a time will become important.
A glitch is a short-lived fault in a system, such as a transient fault that corrects itself, making it difficult to troubleshoot. The term is particularly common in a computing and electronics industries, in circuit bending, as well as among players of video games.
Crazy Credits. Some episodes have different versions of the opening theme. In the Fiona & Cake episodes, it is a gender swapped version of the regular intro with a woman singing the theme song. The episode A Glitch Is a Glitch, the opening is CG animated. In Food Chain, the opening has all the characters with Finn and Jake's faces and the theme song is sung by a different singer as well.