love-in
/ˈlʌvɪn/noun
- informal, dated a gathering or party at which people are encouraged to express feelings of friendship and physical attraction, associated with the hippies of the 1960s〈非正式, 旧〉（20世纪60年代嬉皮士的）爱情聚会。
词源
1960s: originally with reference to Californian hippy gatherings.