water not being free anymore

i cannot make this story up but today this guy walks in and i take his order and he says "can i get a venti ice water" and i b button my manager in the back yknow just asking if i can let it slide but my manager stood his ground (rightfully so as a manager), and told me that id need to charge him. i inform the guy about our new policy and how we'd need to charge him and he gets mad and says he came in yesterday and got it and that i am talking on headset instead of to his face?? he demands the manager come up and then argues with my manager and says something like "ill just go to target then and get an ice water, then i'll know you're lying." this man really goes to target, gets an ice water, comes BACK to my store just to show us that he got an ice water.. at a target starbucks... then says he's going to call corporate on my manager 🤦‍♂️ such jobless behavior bro