shuāngjìnshuāngchū
ㄕㄨㄤ ㄐㄧㄣˋ ㄕㄨㄤ ㄔㄨ
Simplified 双进双出
Taivo → Settings → Partner inbox → Make the link. It stays in this browser.
Keep 雙進雙出 and it comes back until you know it.