You can't be serious! Then what the hell are we doing in this thing called society and community? Any society is held together by rules and those rules are founded upon moral interpretations of what is good and right for that society.
I can give you thirteen examples of just ONE type of law that defined as crimes activities which had no victim and affected nobody but those involved. Until 2003, thirteen states (+ puerto rico, so make it 14) in this country had sodomy laws, 4 of which were applied to homosexuals only, the rest of which applied to both homo and hetro sexuals.
If two adults are consenting to such a practice, and it is done in private, and no harm is done to anyone, by what right does the state or the general public declare such an activity a crime? Upon what moral basis does the public interest invade the private bedroom? What victim is there in such a crime?
Ok, granted, sodomy isn't exactly dinner table discussion - but you asked for an example, and thats one a good hotbutton right there, because I bet you that there are quite a few people who are reading this right now who are thinking, "Well it SHOULD be illegal" and the ONLY basis of that thinking is PERSONAL dislike of the practice. Personal preference is NOT a moral choice, its simply opinion, and should never be the basis of public law.
But we'll call sodomy example #1.
Example #2: Prostitution. In Nevada there are counties (perhaps the whole state, I don't really know, never been there) where prostitution is legal, and there are legal brothels in the state. There are women who work there who bring in six figure incomes and enjoy their work. Their customers have included not only single individuals, but also married and unmarried couples. I'm sure there are also married men who go there without their wives knowing - and while there is a moral wrongness to that, it isn't a reason for a law against prostitution. (And really, should adultery be a CRIMINAL offense? I think divorce courts handle that well enough...)
Nevada is an example of a state where prostitution is legal, safe, and it works. In all other states (to my knowlege) prostitution is illegal. And yet there are women who earn extremely good livings as high class "escorts" who also enjoy their work, and if nobody is hurt (adultery cases aside) and proper protection is used to prevent illness, who is the 'victim' in a case of a man or woman hiring a woman or man (whatever) to satisfy some natural urges?
Example #3: If a person or group of people spend an evening playing cards and smoking a joint, and they stay in one place and don't do something stupid like drive under the influence, who's the victim? But what they've done *IS* a crime in most states. What about the person who depends on marijuana to relieve the pain of cancer or glaucoma? Is smoking a joint a crime? YES, but thats a crime where the act of NOT commiting a crime has a victim - the person who suffers through the pain that isn't necessary.
Do I really need to keep finding more cases? There really are lots more, I just cited some of the biggest ones.