After the movie Its a Wonderful Life, a device whereby an external force (usually supernatural) intervenes in a time of crisis to show the character facing said crisis how things would have been had he or she never been born/entered that line of work/come to town/what have you. May occur as part of a Near-Death Experience, or following Smite Me Oh Mighty Smiter. Episodes with this plot usually take place around Christmas time, because It's a Wonderful Life takes place around Christmas. If a show hasn't done a Yet Another Christmas Carol episode yet, they'll be doing this one.