On behalf of ESL people, you're offended? Maybe you should let them speak for themselves.
Humor is a big part of what makes life worth living. I love it when someone makes me LOL.
Maybe the non-native English speakers just think, "Well, I don't get that, but whatever." In their other reading, they'll run across idiomatic English sooner or later, too.
Don't take life too seriously. You'll never get out of it alive.