Wow, Karen was dumb as a bag of rocks! *spoiler*
The way she dealt with Pete at the end, when she grabbed the gun. Wouldn't most people know it was a test, and would be unloaded?!!
And she wasn't a very good 'actress' around him either at times. But then, while he was a raging psycho stalker yes, she didn't exactly discourage his attentions either!
"I'd say this cloud is Cumulo Nimbus."
"Didn't he discover America?"
"Penfold, shush."