| Swag | Skills or style | 109 |
| SMH | Shaking my head | 159 |
| SOS | Someone over shoulder | 229 |
| sup | What's up | 100 |
| sec | Second | 100 |
| Soccer mom | A suburban mom whose world revolves around her kids | 100 |
| Spam | Unhelpful and annoying content | 100 |
| Sry | Sorry | 100 |
| Selfie | A picture of yourself | 150 |
| SMS | Short Message Service | 100 |
| STD | Sexually transmitted disease | 100 |
| Shook | Completely surprised | 100 |
| SIDS | Sudden infant death syndrome | 200 |
| Sexting | Sending sexually explicit messages | 200 |
| Served | Owned | 200 |
| SWOT | Strengths, weaknesses, opportunities, and threats | 200 |
| Shorty | A fine female | 200 |
| Slide into your DMs | To send a direct message on Twitter | 200 |
| SOS | Save our souls | 260 |
| sis | Sister | 200 |
| SNES | Super Nintendo Entertainment System | 133 |
| Snapstreak | Snapchat streak | 200 |
| SCROTUS | So-called ruler of the United States | 300 |
| str8 | Straight | 200 |
| SOHF | Sense of humor failure | 250 |
| SEO | Search engine optimization | 200 |
| Shotgun | Front passenger seat | 260 |
| SWTOR | Star Wars: The Old Republic | 200 |
| SNL | Saturday Night Live | 200 |
| Shady | Sly | 200 |
| SAT | Scholastic Aptitude Test | 225 |
| Steeze | Style and ease | 133 |
| Skank | A promiscuous woman | 200 |
| SWTLJ | Star Wars: The Last Jedi | 200 |
| Snatched | Perfect | 200 |
| sync | Synchronize | 200 |
| stats | Statistics | 150 |
| s/w | Software | 200 |
| sp | Spelling | 200 |
| SOAD | System of a Down | 200 |
| SCOTUS | Supreme Court of the United States | 240 |
| SSN | Social Security number | 200 |
| Stud | An attractive male | 200 |
| Swerve | Go away | 133 |
| Sack | Bed | 200 |
| SV | Saves | 200 |
| Shade | Disrespect | 200 |
| Selfie stick | An extendable pole with a smartphone on the end | 200 |
| Sugar daddy | An older man used for his money by a woman | 200 |
| Stay woke | Stay aware of social problems | 125 |
| Stay in your lane | Stick to what you're good at | 150 |
| Spammy | Content that features a lot of spam | 200 |
| Sick | Awesome | 200 |
| Side chick | A mistress | 200 |
| Shoot my shot | I'm going for it | 200 |
| sw | Software | 200 |
| SY | Sincerely yours | 150 |
| Stoked | Excited | 200 |
| Sched | Schedule | 200 |
| SG | Sounds good | 260 |
| SERP | Search engine results page | 150 |
| SFF | So freaking funny | 200 |
| ss | Miss | 267 |
| sc2 | StarCraft 2 | 150 |
| sysadmin | System administrator | 300 |
| SH | Same here | 250 |
| SO | Significant other | 255 |
| SOB | Son of a b**** | 200 |
| SOL | S*** out of luck | 300 |
| SOS | Same old stuff | 350 |
| STHU | Shut the heck up | 300 |
| Senioritis | Senior laziness | 325 |
| SWAK | Sealed with a kiss | 300 |
| SAHD | Stay-at-home dad | 300 |
| sysop | System operator (chat monitor) | 300 |
| Speedrunner | A gamer who plays through a video game as fast as possible | 300 |
| spk | Speak | 300 |
| sorta | Sort of | 250 |
| sho | Sure | 250 |
| SYT | See you tomorrow | 300 |
| SNMP | So not my problem | 250 |
| spec | Specialization | 300 |
| SMH | Smash my head | 320 |
| STFW | Search the flippin' Web | 300 |
| SME | Subject matter expert | 300 |
| SSIA | Subject says it all | 167 |
| Spacing | Not paying attention | 300 |
| SMF | So much fun | 300 |
| Sticky | Sticky hand grenade used in the Halo series | 250 |
| stache | Mustache | 250 |
| str | Strength | 300 |
| SHID | Slaps head in disgust | 300 |
| Smooch | Kiss | 300 |
| Snap | Shoot! | 300 |
| SOP | Standard operating procedure | 300 |
| SBT | Sorry 'bout that | 300 |
| sux | Sucks | 300 |
| SOW | Speaking of which | 300 |
| SWA | So what a** | 300 |
| SBTM | Should be there momentarily | 300 |