2māa bit 孖必 — [double beat] police officers patrolling in pairs, the system whereby police officers are supposed to patrol in pairs
3māa gāt 孖吉 — [double seven] the 14K triad society (gāt jí is a triad term for the number seven, triad jargon, OS).
4māa gūng jái 孖公仔 — [twin dolls] two people who are constantly together, two twenty foot containers on a forty foot trailer (truck driver jargon, USi).
5māa lō yàu 孖蘿尤 — [double arse] a policewoman, a woman police officer (police jargon).