夾計 (gaap3 gai2)：collude, to act together secretly (or illegally) in order to deceive or cheat someone
It can be also used in positive way.
我哋夾計，預先冇同佢講就同彼得慶祝生日。
ngo5 dei6 gaap3 gai2 ，jyu6 sin1 mou5 tung4 keoi5 gong2 zau6 tung4 bei2 dak1 hing3 zuk1 saang1 jat6 。
We colluded and celebrate with Peter for his birthday without informing him in advance.
But better to say “Peter 彼得” first in this sentence, then say “him 佢”
我哋夾計，預先冇同彼得講就同佢慶祝生日。
ngo5 dei6 gaap3 gai2 ，jyu6 sin1 mou5 tung4 bei2 dak1 gong2 zau6 tung4 keoi5 hing3 zuk1 saang1 jat6 。
