They think you're wise. And then you talk. This has happened to me (and consequently to those who interacted ad interim) over and over again. Anyway, i'll point out six recent instances where my lack of attention and oversmartassness created unwittingly sitcom-ish scenarios.
Jay: "I don't want any excuses. You have to be at my wedding no matter what."
Me: "Sure, sure. But you'll be there, right?"
Mehv: "That song is from our Coke Studio or yours?"
Me: "Of course, ours. Pakistani Coke Studio."
Saket: "Hi. Saket."
Me: "Naaaa, it's Shakti."
Amma: "When are you planning to grow up?"
Her: "Are you always this foolish?"
Me: "No. Only when i talk."