| cya | See ya | 100 |
| CYE | Check your email | 250 |
| CC | Carbon copy | 200 |
| CTN | Can't talk now | 200 |
| Chicken | Scared | 125 |
| Cab | Taxi | 100 |
| CDC | Centers for Disease Control and Prevention | 233 |
| CPR | Cardiopulmonary resuscitation | 100 |
| COB | Close of business | 325 |
| Cleanup | Player batting fourth in the lineup | 150 |
| CU | See you | 150 |
| CT | Central time zone | 200 |
| CUL | See you later | 367 |
| Creeper | A socially invasive person | 120 |
| combo | Combination | 150 |
| Crying Jordan | A meme featuring a crying Michael Jordan | 133 |
| CSS | Cascading Style Sheet | 150 |
| c | See | 150 |
| CM | Call me | 300 |
| Cinderella | Underdog sports team | 150 |
| Celine a scene | To add a Celine Dion song to a video for maximum emotional impact | 125 |
| char | Character | 150 |
| CEO | Chief executive officer | 200 |
| CST | Central Standard Time | 200 |
| CTC | Call the cell | 200 |
| CMS | Content Management System | 200 |
| cell | Cell phone | 200 |
| CCR | Creedence Clearwater Revival | 200 |
| Cupcaking | Flirting | 200 |
| Cheerio | Goodbye | 200 |
| Cheers | Regards | 250 |
| CYF | Check your Facebook | 200 |
| CG | Computer Graphics | 300 |
| CTE | Chronic traumatic encephalopathy | 200 |
| CTM | Chuckle to myself | 300 |
| Cheesy | Lame humor | 400 |
| cz | Because | 133 |
| CD | Compact disc | 120 |
| comp | Computer | 200 |
| CMIIW | Correct me if I'm wrong | 250 |
| CC | Credit card | 300 |
| cul8r | See you later | 400 |
| CUS | See you soon | 300 |
| cmon | Come on | 300 |
| CYL | Catch ya later | 300 |
| chingo | Chat lingo | 250 |
| COC | Code of conduct | 400 |
| Catfish | To assume a false identity | 300 |
| Crimbo | Christmas | 260 |
| Cougar | An older woman who dates younger men | 150 |
| CID | Consider it done | 400 |
| cuz | Because | 225 |
| CHF | Swiss franc | 350 |
| CU@ | See you around | 300 |
| CUB | Call you back | 350 |
| Cheers | Congratulations | 300 |
| CCG | Collectible card game | 300 |
| Chivette | Female who likes theCHIVE | 250 |
| C&G | Chuckle and grin | 300 |
| CMB | Call me back | 300 |
| CTRN | Can't talk right now | 300 |
| Cow | Minecraft mob | 300 |
| Cracker | A white person | 400 |
| CAC | Cool as a cucumber | 300 |
| CF | Cluster f*** | 250 |
| CX | Correction | 267 |
| C | Catcher | 300 |
| Clutch | Ability to perform under pressure | 140 |
| C2C | Cam to cam | 300 |
| COO | Chief operating officer | 300 |
| C4N | Ciao for now | 300 |
| CAD | Canadian dollar | 250 |
| Card advantage | Possessing more cards than another player | 300 |
| CS | ChatSlang.com | 400 |
| Crapple | Apple | 300 |
| Cray | Crazy | 220 |
| COA | Course of action | 300 |
| Chill | Relax | 175 |
| Crew | Group of friends | 250 |
| CSL | Can't stop laughing | 300 |
| CYO | See you online | 300 |
| CYT | See you tomorrow | 300 |
| cata | Cataclysm | 300 |
| crit | Critical Strike | 300 |
| Chiver | Male who likes theCHIVE | 300 |
| Crib | House | 300 |
| Chillax | Chill and relax | 200 |
| CMU | Crack me up | 300 |
| Cracka | A white person | 300 |
| Cowboy Up | Get tough | 250 |
| CSB | Cool story, bro | 250 |
| CRD | Caucasian Rhythm Disorder | 275 |
| Catch some rays | To go out in the sun | 250 |
| CTC | Care to chat? | 250 |
| Crunk | Crazy and drunk | 300 |
| CRPG | Computer role-playing game | 300 |
| Cycle | Single, double, triple, and home run | 300 |
| Carry | MOBA player role | 250 |
| CF | Center field | 300 |
| CCU | Critical care unit | 300 |