when (usually boys in private schools) gather round and toss each other off

When large numbers of people engage in oral sex in alternating face up/face down positions forming a circular group of people. An individual engaged in daisy chaining will be giving oral sex to one person while receiving oral pleasure from a different person (at the same time). Probably referring to a ring of intertwined bosies having a similar shape and arrangement to a flower arrangement used as a tiara.

British teenagers engaging in a form of group sex The practice involves teenagers going to each others' homes to engage in sex with multiple partners.