She: I’m afraid of dogs.

Me: But this dog is so nice.

She: Nice?  It’s 145 pounds.

Me: I think the chances of the dog falling on top of you are fairly slim.

(Blank stare)
----
They: I can’t believe J. Lo and Ben broke up.

Me: Hey, it’s rough when you’re in a committed, serious relationship and then you make a big budget movie that flops.  We’ve all been there, am I right?

(Blinking)
---
Me: Did someone close that door?

Her: There’s diaper changing going on in the room.

Me: I see.  And are there also babies in there?

(Crickets)
----
Made some others, similar reaction.  So I gave up.  And I was petty enough not to laugh at anyone else’s jokes for the rest of the day, either.