Formerly a slang phrase referring to a male's stated prediliction toward sexual relations with a previously identified female, the phrase has now come to refer to an individual's stated desire to perform sexual relations with a (typically McDonald's) hamburger.
Background: An unfortunate McDonald's advertising campaign, circa early 2005, developed under the assumption that the use of urban lexicon might appeal to a previously underrepresented demographic, i.e., the burger-fetishists.
Vernacular commonly used by males, meaning, «I would NOT MIND having sexual relations with that woman.»
There's a big difference between «I'd hit it..." and "I'd definitely hit it!"; same as between «I'd do her.» and «I'd definitely do her!»
The first sentence indicates that the person who is speaking is moderately interested in the woman in question. The second sentence indicates that the person is considerably interested in the woman, and might swoop down for the kill, if given the opportunity.
Situation #1:
«Wow, is Halle Berry hot, or what?!»
«Yeah, I'd hit it...»
Situation #2:
«Wow, is Halle Berry hot, or what?!»
«Shit yeah, I'd definitely hit it!»
Guy #1: "Man, she's sexy and from what I've heard smart too! I'd like to take her out, embark on a loving long term relationship, and maybe one day, when my words can no longer express how I feel, make beautiful love to her."
Guy #2: "I'd hit it, but if she tries to talk to me after I'll change my number."
Vernacular. Expresses a desire to have sexual relations, usually from the dominant/giving aspect rather than the submissive/receiving one. Implies a lack of personal respect / emotional investment for the person to be "hit." Exact phrase is necessary to carry the meaning. Division, alteration or attempt to use in a literal sense may result in misunderstanding and ridicule.
Common mistakes are made when refering to "a hit" as in a dose of a (usually illegal) non-food chemical compound, or physically striking an object. In such cases, it is preferable to use the actual word for the object to be "hit" over the pronoun "it."