Definitely need to let his parents know. Where would a 16 year old get the money to rent an airB&B in the first place & they don't rent to 16 year olds because they are not a legal age to be in a rental contract agreement.....so who knows what ID he might have stolen to do it in the first place. His parents definitely need to know.

How to do it anonomously is not an easy task. Do you actually know them?

I would probably just straght forward contact them & just say that you have heard what you said here & thought they might want to check into it. Give them the date of the party & location so they know what to look for.

The kid may just be talking big to impress but his parents should know just in case. I wouldn't give all the details of where you got the infirmation but just that this is what you heard. I know if I were his parents I would definitely be going through my credit card accounts to check out the information to see if that is really what is going on. The problem with totally anonomous is that it is easier to blow it off not knowing where the information came from.....but I confront everything directly & diplomatically without accusation just "possible information".....65 years has shown me tbis has been the best way for me to deal with things.