Thats why you first ask, "Have you ever taken the best friends test?" Girls are usually too dumb to remember what it was called, so they might still ask what it is. It's still worth checking first, tho. Once they hear 'shampoo' they'll remember if they'd heard it before. But if they try to call you out, look at them accussingly and be like "That's why I asked you in the beggining if you had ever done this test before? It's pretty common." Now you have put them in their place and taken control again. Don't just act like they stole your line and eject with your tail between your legs.

I'd also wait a little while after opening the set before using old material like the bf test. Because without any rapport built first, everything you say the girls are just looking at you like "Wtf is this guy going on about now?" If its' something they've already heard and it misses its mark, they'll be ready to blow you out without giving you a second chance.

_________________
“Nothing is impossible, the word itself says 'I'm possible'!” ~Audrey Hepburn