Who can forget the Season 3 finale scene that saw Toby (Keegan Allen) tearing up to an angry Spencer (Troian Bellisario)? But what makes Keegan Allen cry on the Pretty Little Liars set? He just tweeted his answer...

Apparently, Troian often brings Keegan to tears... of laughter. In response to the fan question, “Who laughs the most on set?” Keegan answered: “Definitely me. Because of Troian. I'm talking tears.”

Have we mentioned that we love these two together? If you haven’t been exposed to their on-set hijinks, check out the recent Vine series that saw the duo goofing off behind-the-scenes of Season 4, Episode 6: “Under the Gun.” Narratives include: stealing each other’s sunglasses and poking fun at blockbuster trailer soundtracks.

Maybe these two are just happy to be hanging out together after a long stretch of Toby-less episodes last season. We’re psyched that it looks like Spoby will be getting a lot of screen time in Season 4. Keegan recently mentioned that they will start off the season strong, with Spence helping Toby with his difficult past. And they are super cute as crime scene sleuths in this Season 4 premiere sneak peek.

Pretty Little Liars Season 4 premieres on Tuesday, June 11, 2013 at 8 p.m. ET/PT on ABC Family.