Sen. Tim Kaine started off his acceptance speech in Philadelphia tonight with a shout-out to his son, a U.S. Marine who just deployed overseas to, in Kaine’s words, “protect the NATO to protect and defend the very NATO alliesTrump wants to abandon.” Kaine ended it with, “Semper Fi.”

That should have been a good applause line for the gathered Democrats, but it wasn’t — at all.

Here’s NBC’s Chuck Todd:

Um, they should clap? Cheer? Shout, “thank you!”

Maybe they don’t know what it meant?

Michelle Malkin noticed it to:

And from Salena Zito:

Other, too:

Here’s the video so you can see the painful display for yourselves: