This is a fantasy of mine.
Recieving an enema or a colonic in front of a large audiance as part of a lecture or demonstration (rather than a party).
I would lie semi naked under a blanket listening to the lecturer explaining to the group exactly what he/she was going to do to me and then finally undrapes me revealling my bottom to the group. I am then lubed and internally examined by the lecturer (or even better, several examinations by a series of students). I am then penetrated by the nozzle and given my enema with the comentary continuing. Then with the enema complete I get up and nervously scuttle away to find the toilet.