up in (one's) grill

up in (one's) grill

slang Extremely close to one; right up in one's face. (A "grill" is a type of jewelry that adorns the teeth.) I got right up in his grill and told him I would mess him up if he didn't get me my money. I'm a bouncer for a local club, so I'm used to drunk idiots getting up in my grill.
See also: grill, up