One time when booking a flight over the phone (on-line booking in it's infancy) I wanted to use miles to upgrade. Buying flight from PVD-ORD-LAX for me and GF, didn't use the "DYKWIA" line but did ask if I could upgrade because "I didn't belong in coach". Fortunately the agent knew I was attempting to be funny when I said that. Flight was something like $200 each r/t and much to my and the agent's surprise I was able to upgrade the flight with miles.