It is interesting that someone actually feels a need to ask such a question in the context in which it is asked. "....call it on yourself if your opponent didn't see it." I ask the questioner; What do you think?
There are a few odd situations however which call for another look at the question. Here is one such situation:
Suppose you are playing One Pocket and your opponent needs one ball and has game ball hanging deep in his pocket to the point where you know you can't get it out. In addition, there is one or more open balls across the head string which would make scratching with his ball a usless choice of shots. You have no viable shot at your pocket either. What do you do short of surrender?
Well, you might just intentually double hit the cue ball and pocket his hanging eighth ball and stop the cue ball at the lip of the pocket. Now you call a foul on yourself. What is the call in a case like that?
How many of you know the answer?