I said "fetish":

dictionary.com:

fetish

[ fet-ish, occasionally, fee-tish ]SHOW IPA

See synonyms for fetish on Thesaurus.com

noun

any object, part of the body, or activity that is ordinarily regarded as nonsexual and causes a habitual erotic response or fixation.

a habitual erotic response to or fixation on an object, part of the body, or activity ordinarily regarded as nonsexual.

unconventional sexual practices involving an object, part of the body, or activity ordinarily regarded as nonsexual, considered collectively.

THIS ONE HERE:

Anthropology. an object regarded with awe as being the embodiment or habitation of a potent spirit or as having magical potency.

I could say "surrogate" also, with the same meaning.

it's also the basis of most religions, worshipping symbols.

it's the very same thing at play when Pavlov's Dog salivates at the sound of a bell.

the thing and a symbol of the thing have become confused.