For maximum effect, "tag bombs" should occur so that many people see the photo before the victim finds out. This means tag bomb when friends are at work, on vacation, or otherwise preoccupied.
Tag bombs should be in good fun. Tagging a naked photo of you friend might not go over too well. Unless you hate your friends and want them to hate you. Then do what you will.
The photographer uploads the picture onto facebook and tags both people. Rambo immediately untags himself, for obvious reasons. Cole realizes he's the only one still tagged and asks Rambo what's up. Rambo explains he looks stupid and doesn't want people seeing it, and even though he asked photographer to take the picture down or crop him out, photographer wouldn't do it.
Cole waits for when he knows Rambo will be at work. When the time comes, he tags Rambo who won't find out for 6-8 hours, then writes "Tag Bombed Baby!" in the comments section, for good measure.