Murdering misbehaving applications with xkill

Have you ever had a window in Linux freeze on you and no matter how many times you tried to close it, it just wouldn’t go away? Then when you try and find the process in System Monitor (or the like) you can’t seem to identify it for whatever reason? Thankfully there is a really easy to use command that lets you simply click on the offending window and POOF!… it goes away instantly.