Systems Designer Kevin Ralphs liked the CAD tip "Oops — I Did It Again!" so much, he was inspired to share his own trick using the Oops command in AutoCAD.

"Reading Chris Micallef's tip reminded me of a use for the Oops command that I still find handy after a number of years. If for some reason I find I have identical objects on top of one another, and I want to delete the one underneath, I simply erase the top object, move the one remaining to one side, then type Oops. This restores the erased object with its position undisturbed. Then I can erase or otherwise deal with the unwanted moved object. I just have to remember not to use the Erase command again before restoring the wanted object with the Oops command, otherwise it is lost until recovered with the Undo command."
 
Notes from Cadalyst Tip Patrol: The Undo command is my favorite command, but you have to Undo many things to restore deleted objects. Oops is a great alternative: It will restore the last object you deleted. To expand on this tip, if there are several objects on top of each other, you could keep deleting them one at a time until everything was gone, then use the Oops command to bring the last one back.