Is it a good idea to get my bf spanked by other people during in a party? Perhaps with a bit of humiliation element
Is you bf into being spanked? Is he into humiliation? Do you have the sort of relationship which allows you to do kinky or sexual play with other people? Has he ever mentioned (or has he previously done) play with multiple people? If the answer to these are all yes, then go for it (ideally speak to him unless you are sure the surprise would be a great fantasy come true for him). If there you answered no to any, then maybe not a great idea but again, ask him what he thinks about it.
probably not good idea if its a family birthday party