Credit: Shay Mitchell Instagram Photo: Pretty Little Liars 100th Episode Cake

The best thing about a TV show reaching its 100th episode? The cake! And boy does Pretty Little Liars have a good one. You might even call it “A”-mazing.

“Happy 100th episode to our #PLL family and all of you who continue to support!!!” Shay Mitchell (Emily) captioned the Instagram photo of the celebratory cake. The confection is decorated with the four Liars faces and a hovering, ominous, red “A” in the background. “Happy 100th Episode” it reads. Awesome!

In all non-cake-related seriousness, 100 episodes is a big deal for any television show. Traditionally, it has been an important TV landmark because it marks the point at which a show becomes desirable for syndication because it would support 20 weeks of weekday reruns. It’s also impressive in its own right. Few shows make it past the pilot phase. Even fewer shows make it past the first season. And even fewer shows make it to 100 episodes. We’re so proud of Pretty Little Liars!

The 100th episode itself is often a cake for the fans, if you will. Traditionally, the installment will include the return of fan favorite characters, perhaps a retrospective feel , and some big developments. What can we expect from Pretty Little Liars’ 100th episode? Well, the episode was penned by showrunner Marlene King and directed by Norman Buckley, and, according to Marlene: “There will be a big reveal: One of our mysteries that we've had for a long time on the show will be revealed in the 100th." The episode is titled “Miss Me x 100,” so we wonder if this won’t be the episode in which Alison makes her official return to Rosewood and begins trying to reintegrate into “normal” high school life. And both Caleb (Tyler Blackburn) and Jenna (Tammin Sursok) will be returning. Are you excited yet?

Catch the next episode of Pretty Little Liars on Tuesday, June 10, 2014 at 8 p.m. ET on ABC Family.

Kayti Burt is a contributing writer for Wetpaint Entertainment with a penchant for all things pop culture. Follow her on Twitter and Google+!