Nedarim 12 - This to me is like that!
One does not have to say the words "I vow," he can instead say "This to me is like that." For example, if he says, "This bread to me is like the meat of a disqualified offering" - he is then forbidden to eat this bread.
Rami bar Chama asked a question: if one says, "This bread to me is like the meat of a peace offering," - what happens then? Most of the lifetime of the peace offering it is prohibited to eat, so maybe his vow takes effect. But at the end, after its blood has been thrown on the Altar, the meat is eaten by people and guests, so maybe he meant this permitted state, and therefore the vow effects no prohibition?
The Talmud tries to compare this case to various others, where the answer is known, but still does not come with a resolution.
Art: Entertaining the Guests by Pieter Gerardus Sjamaar