I think they have reason to be mad.

When Matt voted for the mystery box and Sheila voted for the mystery box, I thought it was a lock. But nope.
This is like that Family Guy episode on reverse, "The mystery box could be anything! But it couldn't be James!" but yet the person still does the dumb thing, "I'LL TAKE THE JAMES." Now Matt is all "Hey Natalie, where's your vote for the mystery box?" "I didn't take the mystery box. I took the James."
I am rambling. Forgive me.
