I asked my friend to Sadie!! I have a question..?

My friend and I walked over to my date, his best friend (my best friend too), and some other guys. The guy I later asked said "oh I bet (my name) would do that!" I asked what, and he went off on this long random story explanation. This other guy came over and was talking about the dance. Then, when he stopped talking, I asked my date if he has a date for the dance. I wasn't sure haha. He said no an I asked if he wants to go with me. He said sure, smiled really big, ran over to our best friend and said "the plan worked!" then he gave me a hug. I'm super excited! The only thing is..what do you think he meant about the plan?? Haha I'm confused. Thanks!! :)