Who needs a calendar anymore? If you're on Facebook, Twitter, or Instagram you'll know the day of the week simply by the trending hashtag (#).

However, some of the most popular hashtags are acronyms, which may be confusing to know what they mean.

Below is a list of the most popular daily hashtagged acronyms used on social sites.

Sunday:

#SS - SelfieSunday

Sunday's are always nice, gives ya a reason to post a selfie #ss pic.twitter.com/E6dFiDCU8S

— ℋeidi (@Heidi_Gangwish) May 23, 2016

Who doesn't love a good selfie? This acronym is used to share your best selfie with others. So get out your selfie sticks and have at it.

Monday:

#MCM - ManCrushMonday

#MCM goes to #SpiderMan himself, @TomHolland1996 https://t.co/8wkdShqXuU pic.twitter.com/UNGkduewzx

— MTV (@MTV) May 10, 2016

You have a guy you've been crushing on lately? This acronym is used to share about that special man in your life. Doesn't matter if you know them IRL or not. Use this acronym along with a pic of your dreamy dude.

#MM - MusicMonday

Pretty much everyone enjoys listening to an awesome new tune. The #MM acronym is used to share your fav music with everyone in hopes of introducing your jam to a new set of ears.

Tuesday:

#TT - TransformationTuesday

He battled depression and went from ballet to bodybuilding. https://t.co/Kx2mRbhAZu #TransformationTuesday #TT pic.twitter.com/wdZwStEfjm

— Muscle & Fitness (@muscle_fitness) May 10, 2016

This acronym is used to show off your transformation and to inspire others. It primarily pertains to physical fitness achievements or makeup/fashion makeovers but can generally be used for any transformation. The hashtag acronym often accompanies before and after pics to show off the change.

#TT - TravelTuesday

One couple, 7 yrs 40+ countries together, 120+ countries combined. Adventure footage via https://t.co/FaaIpDJ0my #tt pic.twitter.com/NHZrEIG01o

— Savannah Grace (@Sihpromatum) May 13, 2016

You can use this acronym to share your travels with a broader audience than just your followers. It's great for sharing your stories and motivating others to get out and have their own adventures.

Wednesday:

#WCW - WomanCrushWednesday

She lights up the room the moment she walks in.#WCW #PureJoy @Ciara pic.twitter.com/2IRX7Qq1P2

— Russell Wilson (@DangeRussWilson) May 5, 2016

This is the female version of the MCM acronym. It can be used to proclaim to the world that you are currently crushing on a certain lucky lady. And like the MCM acronym, you don't have to actually know the person IRL cause that would just be boring.

#WBW - WayBackWednesday

This acronym was created to steal some thunder from the popular Thursday #TBT acronym. It is used to share a picture from way back in the past to either look back at fond memories or throw shade at your younger self.

Thursday:

#TBT - ThrowbackThursday

#tbt to when I thought my stage clothes were on point/the moment my parents realized I might be partially colorblind pic.twitter.com/AFWSv4bIZQ

— Hunter Hayes (@HunterHayes) May 13, 2016

This acronym is the most popular out of all the daily hashtag acronyms and is the most sentimental one, as well. It functions as a time machine to travel back to a moment in the past. #TBT is often accompanied with a pic to commemorate the past whether it be of their siblings when they were kids or a fond moment with their BFF.

#TT - ThankfulThursday

Along with TBT, this acronym is one of the most sentimental daily hashtags. You can use this to share with others about how thankful you are for a person, pet, event, invention, etc.

Friday:

#FBF - FlashbackFriday

They make me proud every day. #FBF #family #myheart #proudmama pic.twitter.com/salLs5vCSp

— Kris Jenner (@KrisJenner) May 13, 2016

You miss your TBT moment? No problem. The FBF acronym provides a second chance to get in on the nostalgia and take a trip down memory lane.

#FF - FollowFriday or FridayFeeling

The FF acronym is less popular than FBF but you'll still notice it trending on Fridays. You can use it to share with your followers about interesting and entertaining people you follow that they should follow too. It can also be used to share how turnt up you are about the end of the work week.

#TGIF - Thank God it’s Friday

This one is pretty self-explanatory as the TGIF acronym has been around for a while. But it is primarily used to share how excited you are for the end of the work week and beginning of the weekend.

Saturday:

#SS - SocialSaturday, SexySaturday, SaturdaySwag

Saturday is the wild west of all the days as far as trending acronym hashtags go. The day has yet to settle in on a popular acronym. Some of the Saturday trending hashtags include #SocialSaturday (sharing social plans for the day), #SexySaturday (sharing a sexy pic of yourself), and #SaturdaySwag (sharing your sweet swag). Therefore, #SS is probably the most common acronym you’ll see for Saturday along with #SNL, which is used for, you know, SNL.

There are always new acronyms popping up so be sure to check our list of social media slang to stay in the know. And hopefully this guide has helped you better understand all those hashtagged acronyms that keep popping up and filling your feed. So now that you know, get out there and join the conversation! #HAGD