打着朋友的借口玩暧昧
[dă zhe péng yŏu de jiè kŏu wán ài mèi]
'Playing Ambiguity under the Excuse of Friends'. This indicates people who want to build non-clear intimate relationship while pretending that they are still just friends, suggesting subtle games of attraction or flirtation that fall outside the usual norms of either friendship or commitment.