Unnecessary Time Precision

"Rincewind: Exactly how long have you been a barbarian hero? Nijel the Destroyer: Er. What year is this? Rincewind: Out on the road, then? Lost track of time? I know how it is. This is the year of the Hyena. Nijel: Oh, in that case about...about three days."

- Sourcery, Terry Pratchett

Alice asks Bob how long something has been going on. Bob asks Alice what time/day it is, and Alice tells him.

Bob's response then reveals that whatever information Alice gave him is irrelevant.

Not to be confused with Ludicrous Precision.

"Washington: How long have you been here? Church: How long? Um... What day is today? Washington: Today is Tuesday. Church: I've been here 14 months."
 * Red vs. Blue:

"Alan: How about this: When was the last time you called her just to see how she was doing? Charlie: Uh, whoo. What's today, Sunday? Then never."
 * Two and A Half Men

"Butch: When's the last time we beat you up? Alfalfa: Well, let's see...today's the 10th...30 days hath September, April, June and November...it's not a leap year...yesterday."
 * Terry Pratchett uses this trope regularly.
 * In addition to the quote from Sourcery...
 * In Interesting Times, Rincewind asks Cohen the Barbarian how old he is. What century is it? Ninety to 95 years.
 * In Night Watch, Vimes asks when Dibbler Enterprises, Est. was established. What year is it? Tuesday.
 * The Little Rascals movie:

"Interviewer: Well, it's been a year now- Xander: A Year?! It's really been a whole year? What's today? Interviewer: Thursday. Xander: Oh my God, it has been a year."
 * Scrooged: "Listen, I know I haven't talked to you in... *checks watch* ...about 10 or 15 years, but..."
 * Frisky Dingo, Second season:

"Countess Alexandrovna: How long has it been since you've made love to a woman? Boris: What's today? Monday, Tuesday...two years."
 * In Woody Allen's Love and Death:

"Joey: So when do we get to meet the guy? Monica: Let's see, today's Monday... never."
 * Friends, "The One With The Thumb":

"Donna: How many years have you lived in Hawaii Mr. Iowa? Don Iowa: Oh the islands we don't measure time in years but in full moons. Donna: Okay, how many full moons have you lived here? Don Iowa: Hm, about three years worth."
 * Adventures in Odyssey "Aloha Oy!"

"Paul: ...Where are all the other lifeboats, Carl? Carl: Well, judging by the trajectory of the moon and the stars, I'd say... somewhere at the bottom of the ocean. I bit lots of holes in them."
 * Llamas with Hats
 * While not technically time-based, this conversation rings of it: