I had the BBQ on low and just put the burgers and sausage on, closed the lid to allow them to cook and sat down to further socialize. That is when she got up, opened the lid and started fiddling with everything.
I would be worrying that she is one of those people can't just let burgers cook, someone who just HAS to smoosh all the juice out of them. Someone who cannot, for the life of her, figure out why you served hockey pucks at a BBQ.
Oh, I hate that! If I am a guest, and I have a choice, I always go for the sausage because you never know who is a smoosher. Of course, then I run the risk of them punching holes in the sausage.
Sophia, you'd be happy to know that I'm neither a smoosher nor a poker! But the friend who did the cooking was. 
So, she was presumptuous, AND she ruined your meat? I think thats a shooting offense around here. (Kidding, kidding)
Well, she didn't ruin the burgers too much, but because she poked the sausage, she let all the juices out and they were dry.