A butter knife is for cutting things that aren't difficult to cut.
A butter knife (stating the obvious here) is for spreading butter.
A butter knife can be used to loosen the lid of a jar.
A butter knife can be used to jimmy a lock.
A butter knife has many acceptable and proper uses. Such as subbing as a letter opener. That's ok. The following is not ok.
Licking. A BUTTER KNIFE IS NOT TO BE LICKED at the dinner table IN A RESTAURANT (and yes, I AM SHOUTING THIS).
The following is an acutal recount of a Butter Knife Licking Incident. In the end, no one was hurt.
I recently went on a date. I would call it the second date and our first meal together. The gentleman (using the term losely) licked his butter knife. He licked it after thinking about it. He looked at the butter knife, a flash of "do I or don't I" went across his face, and he went for it. It wasn't anywhere near subtle. It was a full-on-slobbering-I-am-going-to-get-everything-stuck-to-this-knife-off-of-this-knife lick. Yes, it was that bad and that obvious. I wish I could say that the talent of his tongue cleaning the knife led my mind to wander to other, we'll call them interesting, thoughts. But it didn't. I was just really grossed out. I wonder if he does it a lot? Lick the butter knife, that is. I will never know.
I know its really tempting to misuse utensils and its probably a little ok in the privacy of your own home. But do not do it in public. On a date. In a crowded restaurant. Resist the urge. Forego the extra sauce or cheese or crusty whatever that is stuck to the knife. Just don't do it.
He did pay for dinner (with money that he fetched from his two-tone-brown-nylon-velcro-closure wallet).