At your father's

While you're thinking where you should test your powers, you hear someone calling your name.
John! Your father is here! You were going to his' this weekend, don't you remember?
Suddenly you get an idea: you, your father, Karen and her daughter and son of 18 and 20 were going to a family party of Karen's family today. You could test it there and take a bit of **** on Karen...