If you really dont care at all about a person doing/taking something you say "knock yourself out" as in to do/eat until you pass out (if you really want to).
Same as "go for it" or "go nuts".
Person 1: "Hey man, can I have some beer?"
Person 2: "Yeah, Knock yourself out"
to incapacitate or render oneself unconscious by means of physical, or mental, abuse or deprivation to one's own body.
"You are ridiculous. Knock yourself out now!"
"There is no way I can win this race. I might as well knock myself out!"
"I was about to kick that guy's ass for the way he was talking to my girlfriend, but he knocked himself out already."
Utility beer is the beer you keep around for the day-to-day moments when beer is a necessity to assist in pedestrian activities (golf, plumbing, yardwork, babysitting, staff meetings, Zoom calls). For the beer snob it is the beer you save for neighbors when they drop in at 3 p.m. on a Tuesday. It is differentiated from the actual high-end beer you save for special events, holidays, and special tastings.
Person 1: Dave, did you bring along those hazy craft IPA's so we could drink while cleaning Lyle's pool?
Person 2: Nope. I just have a bunch of utility beer that Steve dumped on me. Good enough for this. It is only 10:30 a.m.