OP here. Thanks for the comments everyone, you'll be pleased to hear that today I did phone up the restaurant posing as 'a member of the girl's team' (which is technically true), as I didn't want to identify myself. I can take a bit of banter as much as the next person, and although I'm sure it was meant as a joke, it certainly crossed a line. I thought I'd say something to his manager in case he repeated his actions to someone less capable of standing up for themselves than me! You never know who he might try it with again... The (female) owner was horrified and said she was furious with the waiter, who had apparently worked there for 20 years. She'll be having a chat with him later on and offered me and 'the girl' (also me!) a free pizza each. I don't think I'll be taking them up on the offer! Oh, and my team were lovely about it- after the shocked silence they all agreed that he crossed a line and were very supportive :)