If you use short variable names for loop variables and stuff, you can code faster because you type quicker.
Back in college, I had to rename i,j,k,l as indx,jndx,kndx,lndx just to keep the TAs off my back. Single char variable names were FORBIDDEN!! but they never had a good reason for ruining the readability of the code when a quick comment at most would serve to describe which index variable was which.
You might notice that Mathematics texts never use long variable names, and COBOL always does? Nuff said.
Also globals aren't bad, and public variables aren't bad.
Of course they are bad. Necessary sometimes, but bad. So write yourself a comment as to why you are using it, and go on, and let someone else remove it after you have left the company, if they have nothing else to do with their lives. Especially useful for tracking internal conditions in functions when you are debugging and don't want to bother stepping through them.