The phrase "We Are Bounce Under 18s" refers to a UK-based community and event series specifically organized for those under the age of 18 who enjoy bounce music and commercial dance music. These events focus on providing a safe and energetic environment for younger audiences to gather and enjoy rave-style parties with top DJs and bounce anthems. The "bounce" here relates to a genre of high-energy dance music popular at these events. It is essentially an under-18s rave or dance event brand known for hosting music events across the UK with an emphasis on bounce music culture and youth-friendly settings.

Thus, "We Are Bounce Under 18s" is not just a phrase but the name and description of a targeted music event community dedicated to under-18 audiences who love bounce music and live dance experiences.