| M2NY | Me Too, Not Yet | - | ISO Country Codes |
| M4C | Meet For Coffee | - | ISO Country Codes |
| M8 | Mate | - | ISO Country Codes |
| M8S | Mates | - | ISO Country Codes |
| MA | Mature Audience | - | ISO Country Codes |
| MAYA | Most Advanced Yet Accessible | - | ISO Country Codes |
| MB | Message Board | - | ISO Country Codes |
| MBN | Must Be Nice | - | ISO Country Codes |
| MBRFN | Must Be Real F*cking Nice | - | ISO Country Codes |
| MC | Merry Christmas | - | ISO Country Codes |
| MEGO | My Eyes Glaze Over | - | ISO Country Codes |
| MEH | Who Cares Or Whatever | - | ISO Country Codes |
| MFD | Multi-Function Device | - | ISO Country Codes |
| MFIC | Mother F*cker In Charge | - | ISO Country Codes |
| MFWIC | Mo Fo Who's In Charge | - | ISO Country Codes |
| MGB | May God Bless | - | ISO Country Codes |
| MHBFY | My Heart Bleeds For You | - | ISO Country Codes |
| MHOTY | My Hat's Off To You | - | ISO Country Codes |
| MIA | Missing In Action | - | ISO Country Codes |
| MIHAP | May I Have Your Attention Please | - | ISO Country Codes |
| MIL | Mother-In-Law | - | ISO Country Codes |
| MILF | Mother I'd Like To F*ck | - | ISO Country Codes |
| MIRL | Meet In Real Life | - | ISO Country Codes |
| MITIN | More Info Than I Needed | - | ISO Country Codes |
| MKOP | My Kind Of Place | - | ISO Country Codes |
| MLA | Multiple Letter Acronym | - | ISO Country Codes |
| MLAS | My Lips Are Sealed | - | ISO Country Codes |
| MM | Market Maker | - | ISO Country Codes |
| MMHA2U | My Most Humble Apologies To You | - | ISO Country Codes |
| MO | Move On | - | ISO Country Codes |
| MOF | Matter Of Fact | - | ISO Country Codes |
| MOFO | Mother F*cker | - | ISO Country Codes |
| MOMPL | MOMent PLease | - | ISO Country Codes |
| MOOS | Member Of The Opposite Sex | - | ISO Country Codes |
| MOP | MOment Please | - | ISO Country Codes |
| MORF | Male Or Female | - | ISO Country Codes |
| MOS | Mom Over Shoulder | - | ISO Country Codes |
| MOSS | Member(s) Of The Same Sex | - | ISO Country Codes |
| MOTAS | Member Of The Appropriate Sex | - | ISO Country Codes |
| MOTD | Message Of The Day | - | ISO Country Codes |
| MOTOS | Member(s) Of The Opposite Sex | - | ISO Country Codes |
| MOTSS | Member(s) Of The Same Sex | - | ISO Country Codes |
| MPFB | My Personal F*ck Buddy | - | ISO Country Codes |
| MRA | Moving Right Along | - | ISO Country Codes |
| MSG | Message | - | ISO Country Codes |
| MSMD | Monkey See Monkey Do | - | ISO Country Codes |
| MSNUW | Mini-Skirt No UnderWear | - | ISO Country Codes |
| MTBF | Mean Time Before Failure | - | ISO Country Codes |
| MTF | More To Follow | - | ISO Country Codes |
| MTFBWY | May The Force Be With You | - | ISO Country Codes |
| MTLA | My True Love Always | - | ISO Country Codes |
| MTSBWY | May The Schwartz Be With You | - | ISO Country Codes |
| MUAH | The Sound Of A Kiss | - | ISO Country Codes |
| MUBAR | Messed Up Beyond All Recognition | - | ISO Country Codes |
| MUSM | Miss You So Much | - | ISO Country Codes |
| MWAH | The Sound Of A Kiss | - | ISO Country Codes |
| MWBRL | More Will Be Revealed Later | - | ISO Country Codes |
| MYL | Mind Your Language | - | ISO Country Codes |
| MYOB | Mind Your Own Business | - | ISO Country Codes |
