Me: Which WiFi are we on?
Coworker: Should be floor 89.
Me: What about flight 104?
Coworker: Oh crap!
Me: Which WiFi are we on?
Coworker: Should be floor 89.
Me: What about flight 104?
Coworker: Oh crap!
Listen up, buttercup. The joke is about the Twin Towers and 9/11. Get it? The coworker mentions floor 89, implying they're in a tall building, like the Twin Towers. Then the person asks about "flight 104," which is a dark reference to the planes that crashed into the towers. The coworker's "oh crap" is the realization of the 9/11 reference. You probably still don't get it, do you?